Add crash logger

.gitignore

@@ -2,4 +2,5 @@
 *.out
 *.exe
 *.db
-*.pem
+*.pem
+crash_*.txt

Makefile

@@ -5,7 +5,7 @@ ifeq ($(OS),Windows_NT)
 	FLAGS += -lws2_32 -lbcrypt
 else
 	EXT = .out
-	FLAGS += -lssl -lcrypto -DHTTPS_ENABLED
+	FLAGS += -lssl -lcrypto -fno-omit-frame-pointer -gdwarf-3 -DHTTPS_ENABLED
 endif
 
 all: cweb.h cozisnews$(EXT)

amalg.py

@@ -52,6 +52,7 @@ OTHER DEALINGS IN THE SOFTWARE.
 
 header.append_text("#ifndef CWEB_INCLUDED\n")
 header.append_text("#define CWEB_INCLUDED\n")
+header.append_text("#define _GNU_SOURCE")
 header.append_file("src/main.h")
 header.append_text("#endif // CWEB_INCLUDED\n")
 

cweb.h

@@ -1,8 +1,8 @@
 /*
-Copyright © 2025 Francesco Cozzuto
+Copyright © 2025 Francesco Cozzuto
 
 Permission is hereby granted, free of charge, to any person obtaining a
-copy of this software and associated documentation files (the “Software”),
+copy of this software and associated documentation files (the “Software”),
 to deal in the Software without restriction, including without limitation
 the rights to use, copy, modify, merge, publish, distribute, sublicense,
 and/or sell copies of the Software, and to permit persons to whom the
@@ -11,7 +11,7 @@ Software is furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included
 in all copies or substantial portions of the Software.
 
-THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS
 OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
@@ -21,7 +21,7 @@ OTHER DEALINGS IN THE SOFTWARE.
 */
 #ifndef CWEB_INCLUDED
 #define CWEB_INCLUDED
-
+#define _GNU_SOURCE
 ////////////////////////////////////////////////////////////////////////////////////////
 // src/main.h
 ////////////////////////////////////////////////////////////////////////////////////////
@@ -250,6 +250,8 @@ typedef struct CWEB_Request CWEB_Request;
 int  cweb_global_init(void);
 void cweb_global_free(void);
 
+void cweb_enable_crash_logger(CWEB_String file);
+
 // TODO: comment
 CWEB *cweb_init(CWEB_String addr, uint16_t port, uint16_t secure_port,
     CWEB_String cert_key, CWEB_String private_key);
@@ -13093,13 +13095,15 @@ char *_crypt_gensalt_blowfish_rn(const char *prefix, unsigned long count,
 #include <limits.h>
 #include <stdlib.h>
 
-#ifdef __linux__
-#include <errno.h>
-#include <sys/random.h>
-#endif
-
 #ifdef _WIN32
 #include <windows.h>
+#else
+#include <link.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <signal.h>
+#include <execinfo.h>
+#include <sys/random.h>
 #endif
 
 #ifdef CWEB_ENABLE_DATABASE
@@ -13120,6 +13124,9 @@ char *_crypt_gensalt_blowfish_rn(const char *prefix, unsigned long count,
 #define TRACE(X, ...) ((void) 0)
 #define SIZEOF(X) (int) (sizeof(X)/sizeof((X)[0]))
 
+static int  crash_logger_init(char *file_name, int file_name_len);
+static void crash_logger_free(void);
+
 #ifdef CWEB_ENABLE_TEMPLATE
 
 typedef struct {
@@ -14174,6 +14181,7 @@ int cweb_global_init(void)
 void cweb_global_free(void)
 {
     http_global_free();
+    crash_logger_free();
 }
 
 CWEB *cweb_init(CWEB_String addr, uint16_t port, uint16_t secure_port,
@@ -14349,6 +14357,12 @@ int cweb_enable_database(CWEB *cweb, CWEB_String database_file, CWEB_String sche
 #endif
 }
 
+void cweb_enable_crash_logger(CWEB_String file)
+{
+    if (crash_logger_init(file.ptr, file.len) < 0)
+        printf("WARNING: Failed to set up crash logger\n");
+}
+
 CWEB_Request *cweb_wait(CWEB *cweb)
 {
     CWEB_Request *req = &cweb->req;
@@ -14561,7 +14575,7 @@ CWEB_String cweb_get_csrf(CWEB_Request *req)
     return req->csrf;
 }
 
-/////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
 // TEMPLATE
 ////////////////////////////////////////////////////////////////
 #ifdef CWEB_ENABLE_TEMPLATE
@@ -14926,4 +14940,439 @@ void cweb_respond_template_impl(CWEB_Request *req, int status, CWEB_String templ
     http_response_builder_done(req->builder);
 #endif
 }
+
+////////////////////////////////////////////////////////////////
+// CRASH LOGGER
+////////////////////////////////////////////////////////////////
+#if defined(__linux__) && defined(__x86_64__)
+
+#define _GNU_SOURCE
+#include <elf.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/reg.h>
+#include <sys/stat.h>
+#include <ucontext.h>
+
+typedef struct {
+    uint64_t base_addr;
+    int count;
+    void *symbols;
+    void *strings;
+} SymbolTable;
+
+static int is_hex(char c)
+{
+    return (c >= '0' && c <= '9') || 
+           (c >= 'a' && c <= 'f') || 
+           (c >= 'A' && c <= 'F');
+}
+
+static uint64_t query_base_addr(void)
+{
+    int fd = open("/proc/self/maps", O_RDONLY);
+    if (fd < 0) 
+        return -1;
+
+    char buf[128];
+    int ret = read(fd, buf, sizeof(buf));
+    if (ret < 0) {
+        close(fd);
+        return -1;
+    }
+
+    close(fd);
+
+    if (ret == 0 || !is_hex(buf[0]))
+        return -1;
+
+    int i = 0;
+    uint64_t base_addr = 0;
+    for (;;) {
+        char c = buf[i++];
+
+        int d;
+        if (0) {}
+        else if (c >= 'a' && c <= 'f') d = c - 'a' + 10;
+        else if (c >= 'A' && c <= 'F') d = c - 'A' + 10;
+        else d = c - '0';
+
+        if (base_addr > (UINT64_MAX - d) / 16)
+            return -1;
+        base_addr = base_addr * 16 + d;
+
+        if (i == ret)
+            return -1;
+
+        if (buf[i] == '-')
+            break;
+
+        if (!is_hex(buf[i]))
+            return -1;
+    }
+
+    return base_addr;
+}
+
+static int current_executable_path(char *dst, int cap)
+{
+    if (cap == 0)
+        return -1;
+
+    int ret = readlink("/proc/self/exe", dst, cap-1);
+    if (ret < 0)
+        return -1;
+    dst[ret] = '\0';
+    return ret;
+}
+
+static int load_symbols_from_elf(void *src, int len, SymbolTable *st)
+{
+    // NOTE: It's assumed is properly aligned
+    assert(((uintptr_t) src & 15) == 0);
+
+    // Check that the file contains a full header
+    if (len < (int) sizeof(Elf64_Ehdr))
+        return -1;
+    Elf64_Ehdr *ehdr = (Elf64_Ehdr*) src;
+
+    // Check that the file contains the full list
+    // of section headers
+    if (ehdr->e_shoff + ehdr->e_shnum * sizeof(Elf64_Shdr) > len)
+        return -1;
+    Elf64_Shdr *shdrs = (Elf64_Shdr*) (src + ehdr->e_shoff);
+
+    Elf64_Shdr *shstrtab_hdr = &shdrs[ehdr->e_shstrndx]; // TODO: bounds check
+    char *shstrtab = src + shstrtab_hdr->sh_offset;
+
+    // Iterate over the section headers to find the
+    // one reative to symbols and their strings
+    Elf64_Shdr *symtab_hdr = NULL;
+    Elf64_Shdr *strtab_hdr = NULL;
+
+    for (int i = 0; i < ehdr->e_shnum; i++) {
+        char *section_name = shstrtab + shdrs[i].sh_name;
+        if (0) {}
+        else if (!strcmp(section_name, ".symtab")) symtab_hdr = &shdrs[i];
+        else if (!strcmp(section_name, ".strtab")) strtab_hdr = &shdrs[i];
+    }
+
+    if (symtab_hdr == NULL || strtab_hdr == NULL) {
+        return -1;
+    }
+
+    void *mem = malloc(symtab_hdr->sh_size + strtab_hdr->sh_size);
+    if (mem == NULL) {
+        return -1;
+    }
+
+    st->count = symtab_hdr->sh_size / sizeof(Elf64_Sym);
+    st->symbols = mem;
+    st->strings = (char*) st->symbols + symtab_hdr->sh_size;
+
+    memcpy(st->symbols, src + symtab_hdr->sh_offset, symtab_hdr->sh_size);
+    memcpy(st->strings, src + strtab_hdr->sh_offset, strtab_hdr->sh_size);
+
+    return 0;
+}
+
+static char *read_file(char *path, int *len)
+{
+    int fd = open(path, O_RDONLY);
+    if (fd < 0)
+        return NULL;
+
+    struct stat buf;
+    if (fstat(fd, &buf) < 0) {
+        close(fd);
+        return NULL;
+    }
+    *len = buf.st_size;
+
+    char *ptr = malloc(*len + 1);
+    if (ptr == NULL) {
+        close(fd);
+        return NULL;
+    }
+
+    for (int num = 0; num < *len; ) {
+
+        int ret = read(fd, ptr + num, *len - num);
+        if (ret <= 0) {
+            free(ptr);
+            close(fd);
+            return NULL;
+        }
+
+        num += ret;
+    }
+
+    ptr[*len] = '\0';
+    return ptr;
+}
+
+static int symbol_table_from_current_process(SymbolTable *st)
+{
+    uint64_t base_addr = query_base_addr();
+    if (base_addr == -1)
+        return -1;
+    st->base_addr = base_addr;
+
+    char path[1<<10];
+    if (current_executable_path(path, sizeof(path)) < 0)
+        return -1;
+
+    char *exe_ptr;
+    int   exe_len;
+    exe_ptr = read_file(path, &exe_len);
+    if (exe_ptr == NULL)
+        return -1;
+
+    if (load_symbols_from_elf(exe_ptr, exe_len, st) < 0) {
+        free(exe_ptr);
+        return -1;
+    }
+
+    free(exe_ptr);
+    return 0;
+}
+
+static void symbol_table_free(SymbolTable *st)
+{
+    free(st->symbols);
+}
+
+static char *symbol_table_find(SymbolTable *st, uint64_t addr)
+{
+    for (int i = 0; i < st->count; i++) {
+        Elf64_Sym *sym = (Elf64_Sym*) st->symbols + i;
+
+        if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+            continue;
+
+        if (sym->st_value == 0)
+            continue;
+
+        uint64_t sym_beg = st->base_addr + sym->st_value;
+        uint64_t sym_end = st->base_addr + sym->st_value + sym->st_size;
+
+        if (addr >= sym_beg && addr < sym_end)
+            return (char*) st->strings + sym->st_name;
+    }
+
+    return NULL;
+}
+
+#if 0
+static void symbol_table_dump(SymbolTable *st)
+{
+    for (int i = 0; i < st->count; i++) {
+        Elf64_Sym *sym = (Elf64_Sym*) st->symbols + i;
+
+        if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+            continue;
+
+        if (sym->st_value == 0)
+            continue;
+
+        char *name = (char*) st->strings + sym->st_name;
+        printf("%s\n", name);
+    }
+}
+#endif
+
+typedef struct {
+    char    *name;
+    uint64_t addr;
+} StackFrame;
+
+static int walk_stack(uint64_t rip, uint64_t rbp, SymbolTable *st, StackFrame *frames, int max_frames)
+{
+    int frame_count = 0;
+
+    if (frame_count < max_frames) {
+        frames[frame_count].addr = rip - st->base_addr;
+        frames[frame_count].name = symbol_table_find(st, rip);
+        frame_count++;
+    }
+
+    while (rbp != 0) {
+
+        if (rbp & 0xF)
+            break;
+
+        uint64_t *frame_ptr = (uint64_t*) rbp;
+
+        uint64_t next_rbp    = frame_ptr[0];
+        uint64_t return_addr = frame_ptr[1];
+
+        if (next_rbp != 0 && next_rbp <= rbp)
+            break;
+
+        if (return_addr == 0)
+            break;
+
+        if (frame_count == max_frames)
+            break;
+        frames[frame_count].addr = return_addr - st->base_addr;
+        frames[frame_count].name = symbol_table_find(st, return_addr);
+        frame_count++;
+
+        rbp = next_rbp;
+    }
+
+    return frame_count;
+}
+
+static bool        crash_logger_symbol_init = false;
+static char*       crash_logger_file_name = NULL;
+static SymbolTable crash_logger_symbol_table;
+static char*       crash_logger_signal_stack;
+
+static void crash_handler(int sig, siginfo_t *info, void *ucontext)
+{
+    if (crash_logger_symbol_init) {
+
+        // Buffer for evaluating format strings
+        char tmp[1<<9];
+        int len;
+
+        ucontext_t *ctx = (ucontext_t*) ucontext;
+        uint64_t rip = ctx->uc_mcontext.gregs[REG_RIP];
+        uint64_t rbp = ctx->uc_mcontext.gregs[REG_RBP];
+
+        StackFrame frames[64];
+        int count = walk_stack(rip, rbp, &crash_logger_symbol_table, frames, 64);
+
+        int fd = open(crash_logger_file_name, O_WRONLY | O_CREAT, 0666);
+        if (fd < 0)
+            exit(1);
+
+        CWEB_String sig_name = {0};
+        switch (sig) {
+            case SIGSEGV: sig_name = CWEB_STR("Segmentation fault");       break;
+            case SIGBUS : sig_name = CWEB_STR("Bus error");                break;
+            case SIGILL : sig_name = CWEB_STR("Illegal instruction");      break;
+            case SIGFPE : sig_name = CWEB_STR("Floating point exception"); break;
+            case SIGTRAP: sig_name = CWEB_STR("Trace trap");               break;
+            case SIGSYS : sig_name = CWEB_STR("Bad system call");          break;
+            case SIGABRT: sig_name = CWEB_STR("Abort");                    break;
+        }
+        if (sig_name.len == 0) {
+            len = snprintf(tmp, sizeof(tmp), "(unknown signal %d)\n", sig);
+            write(fd, tmp, len);
+        } else {
+            write(fd, sig_name.ptr, sig_name.len);
+            write(fd, "\n", 1);
+        }
+
+        for (int i = 0; i < count; i++) {
+            len = snprintf(tmp, sizeof(tmp), "  [%d] 0x%lx %s\n", i, frames[i].addr, 
+                frames[i].name ? frames[i].name : "?");
+            write(fd, tmp, len);
+        }
+
+        close(fd);
+    }
+    exit(1);
+}
+
+static int crash_logger_init(char *file_name, int file_name_len)
+{
+    {
+        char *file_name_copy = malloc(file_name_len + 1);
+        if (file_name_copy == NULL)
+            return -1;
+        memcpy(file_name_copy, file_name, file_name_len);
+        file_name_copy[file_name_len] = '\0';
+        crash_logger_file_name = file_name_copy;
+    }
+
+    if (symbol_table_from_current_process(&crash_logger_symbol_table) < 0) {
+        free(crash_logger_file_name);
+        return -1;
+    }
+
+    // Set up alternate signal stack
+    {
+        crash_logger_signal_stack = malloc(SIGSTKSZ);
+        if (crash_logger_signal_stack == NULL) {
+            symbol_table_free(&crash_logger_symbol_table);
+            free(crash_logger_file_name);
+            return -1;
+        }
+
+        stack_t ss;
+        ss.ss_sp = crash_logger_signal_stack;
+        ss.ss_size = SIGSTKSZ;
+        ss.ss_flags = 0;
+        if (sigaltstack(&ss, NULL) < 0) {
+            free(crash_logger_signal_stack);
+            symbol_table_free(&crash_logger_symbol_table);
+            free(crash_logger_file_name);
+            return -1;
+        }
+    }
+
+    {
+        // Register the crash handler
+        struct sigaction sa;
+        sa.sa_sigaction = crash_handler;
+        sa.sa_flags = SA_SIGINFO | SA_ONSTACK;  // Add SA_ONSTACK flag
+        sigemptyset(&sa.sa_mask);
+
+        // Memory errors
+        sigaction(SIGSEGV, &sa, NULL);  // Segmentation fault (invalid memory access)
+        sigaction(SIGBUS, &sa, NULL);   // Bus error (misaligned access, hardware error)
+
+        // Execution errors
+        sigaction(SIGILL, &sa, NULL);   // Illegal instruction
+        sigaction(SIGFPE, &sa, NULL);   // Floating point exception
+        sigaction(SIGTRAP, &sa, NULL);  // Trace trap
+
+        // System/resource errors
+        sigaction(SIGSYS, &sa, NULL);   // Bad system call
+        sigaction(SIGABRT, &sa, NULL);  // Abort (from assert, abort(), etc.)
+
+        // Optional: Resource limit violations
+        sigaction(SIGXCPU, &sa, NULL);  // CPU time limit exceeded
+        sigaction(SIGXFSZ, &sa, NULL);  // File size limit exceeded
+    }
+
+    crash_logger_symbol_init = true;
+    return 0;
+}
+
+static void crash_logger_free(void)
+{
+    if (!crash_logger_symbol_init)
+        return;
+
+    free(crash_logger_signal_stack);
+    symbol_table_free(&crash_logger_symbol_table);
+    free(crash_logger_file_name);
+
+    crash_logger_symbol_init = false;
+}
+
+#else
+
+static int crash_logger_init(char *file_name, int file_name_len)
+{
+    (void) file_name;
+    (void) file_name_len;
+    return -1;
+}
+
+static void crash_logger_free(void)
+{
+}
+
+#endif
 #endif // CWEB_IMPLEMENTATION

demo/main.c

@@ -248,6 +248,8 @@ static void endpoint_index(CWEB *cweb, CWEB_Request *req)
 {
     (void) cweb;
 
+    __builtin_trap(); // TODO: remove me
+
     cweb_respond_template(req, 200, CWEB_STR("demo/pages/index.wl"));
 }
 
@@ -335,6 +337,10 @@ int main(void)
     if (cweb_global_init() < 0)
         return -1;
 
+    char buf[128];
+    int len = snprintf(buf, sizeof(buf), "crash_%d.txt", getpid());
+    cweb_enable_crash_logger((CWEB_String) { buf, len });
+
     uint16_t    secure_port = 0;
     CWEB_String cert_key;
     CWEB_String private_key;

src/main.c

@@ -2,13 +2,15 @@
 #include <limits.h>
 #include <stdlib.h>
 
-#ifdef __linux__
-#include <errno.h>
-#include <sys/random.h>
-#endif
-
 #ifdef _WIN32
 #include <windows.h>
+#else
+#include <link.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <signal.h>
+#include <execinfo.h>
+#include <sys/random.h>
 #endif
 
 #ifdef CWEB_ENABLE_DATABASE
@@ -29,6 +31,9 @@
 #define TRACE(X, ...) ((void) 0)
 #define SIZEOF(X) (int) (sizeof(X)/sizeof((X)[0]))
 
+static int  crash_logger_init(char *file_name, int file_name_len);
+static void crash_logger_free(void);
+
 #ifdef CWEB_ENABLE_TEMPLATE
 
 typedef struct {
@@ -1083,6 +1088,7 @@ int cweb_global_init(void)
 void cweb_global_free(void)
 {
     http_global_free();
+    crash_logger_free();
 }
 
 CWEB *cweb_init(CWEB_String addr, uint16_t port, uint16_t secure_port,
@@ -1258,6 +1264,12 @@ int cweb_enable_database(CWEB *cweb, CWEB_String database_file, CWEB_String sche
 #endif
 }
 
+void cweb_enable_crash_logger(CWEB_String file)
+{
+    if (crash_logger_init(file.ptr, file.len) < 0)
+        printf("WARNING: Failed to set up crash logger\n");
+}
+
 CWEB_Request *cweb_wait(CWEB *cweb)
 {
     CWEB_Request *req = &cweb->req;
@@ -1470,7 +1482,7 @@ CWEB_String cweb_get_csrf(CWEB_Request *req)
     return req->csrf;
 }
 
-/////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
 // TEMPLATE
 ////////////////////////////////////////////////////////////////
 #ifdef CWEB_ENABLE_TEMPLATE
@@ -1835,3 +1847,438 @@ void cweb_respond_template_impl(CWEB_Request *req, int status, CWEB_String templ
     http_response_builder_done(req->builder);
 #endif
 }
+
+////////////////////////////////////////////////////////////////
+// CRASH LOGGER
+////////////////////////////////////////////////////////////////
+#if defined(__linux__) && defined(__x86_64__)
+
+#define _GNU_SOURCE
+#include <elf.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/reg.h>
+#include <sys/stat.h>
+#include <ucontext.h>
+
+typedef struct {
+    uint64_t base_addr;
+    int count;
+    void *symbols;
+    void *strings;
+} SymbolTable;
+
+static int is_hex(char c)
+{
+    return (c >= '0' && c <= '9') || 
+           (c >= 'a' && c <= 'f') || 
+           (c >= 'A' && c <= 'F');
+}
+
+static uint64_t query_base_addr(void)
+{
+    int fd = open("/proc/self/maps", O_RDONLY);
+    if (fd < 0) 
+        return -1;
+
+    char buf[128];
+    int ret = read(fd, buf, sizeof(buf));
+    if (ret < 0) {
+        close(fd);
+        return -1;
+    }
+
+    close(fd);
+
+    if (ret == 0 || !is_hex(buf[0]))
+        return -1;
+
+    int i = 0;
+    uint64_t base_addr = 0;
+    for (;;) {
+        char c = buf[i++];
+
+        int d;
+        if (0) {}
+        else if (c >= 'a' && c <= 'f') d = c - 'a' + 10;
+        else if (c >= 'A' && c <= 'F') d = c - 'A' + 10;
+        else d = c - '0';
+
+        if (base_addr > (UINT64_MAX - d) / 16)
+            return -1;
+        base_addr = base_addr * 16 + d;
+
+        if (i == ret)
+            return -1;
+
+        if (buf[i] == '-')
+            break;
+
+        if (!is_hex(buf[i]))
+            return -1;
+    }
+
+    return base_addr;
+}
+
+static int current_executable_path(char *dst, int cap)
+{
+    if (cap == 0)
+        return -1;
+
+    int ret = readlink("/proc/self/exe", dst, cap-1);
+    if (ret < 0)
+        return -1;
+    dst[ret] = '\0';
+    return ret;
+}
+
+static int load_symbols_from_elf(void *src, int len, SymbolTable *st)
+{
+    // NOTE: It's assumed is properly aligned
+    assert(((uintptr_t) src & 15) == 0);
+
+    // Check that the file contains a full header
+    if (len < (int) sizeof(Elf64_Ehdr))
+        return -1;
+    Elf64_Ehdr *ehdr = (Elf64_Ehdr*) src;
+
+    // Check that the file contains the full list
+    // of section headers
+    if (ehdr->e_shoff + ehdr->e_shnum * sizeof(Elf64_Shdr) > len)
+        return -1;
+    Elf64_Shdr *shdrs = (Elf64_Shdr*) (src + ehdr->e_shoff);
+
+    Elf64_Shdr *shstrtab_hdr = &shdrs[ehdr->e_shstrndx]; // TODO: bounds check
+    char *shstrtab = src + shstrtab_hdr->sh_offset;
+
+    // Iterate over the section headers to find the
+    // one reative to symbols and their strings
+    Elf64_Shdr *symtab_hdr = NULL;
+    Elf64_Shdr *strtab_hdr = NULL;
+
+    for (int i = 0; i < ehdr->e_shnum; i++) {
+        char *section_name = shstrtab + shdrs[i].sh_name;
+        if (0) {}
+        else if (!strcmp(section_name, ".symtab")) symtab_hdr = &shdrs[i];
+        else if (!strcmp(section_name, ".strtab")) strtab_hdr = &shdrs[i];
+    }
+
+    if (symtab_hdr == NULL || strtab_hdr == NULL) {
+        return -1;
+    }
+
+    void *mem = malloc(symtab_hdr->sh_size + strtab_hdr->sh_size);
+    if (mem == NULL) {
+        return -1;
+    }
+
+    st->count = symtab_hdr->sh_size / sizeof(Elf64_Sym);
+    st->symbols = mem;
+    st->strings = (char*) st->symbols + symtab_hdr->sh_size;
+
+    memcpy(st->symbols, src + symtab_hdr->sh_offset, symtab_hdr->sh_size);
+    memcpy(st->strings, src + strtab_hdr->sh_offset, strtab_hdr->sh_size);
+
+    return 0;
+}
+
+static char *read_file(char *path, int *len)
+{
+    int fd = open(path, O_RDONLY);
+    if (fd < 0)
+        return NULL;
+
+    struct stat buf;
+    if (fstat(fd, &buf) < 0) {
+        close(fd);
+        return NULL;
+    }
+    *len = buf.st_size;
+
+    char *ptr = malloc(*len + 1);
+    if (ptr == NULL) {
+        close(fd);
+        return NULL;
+    }
+
+    for (int num = 0; num < *len; ) {
+
+        int ret = read(fd, ptr + num, *len - num);
+        if (ret <= 0) {
+            free(ptr);
+            close(fd);
+            return NULL;
+        }
+
+        num += ret;
+    }
+
+    ptr[*len] = '\0';
+    return ptr;
+}
+
+static int symbol_table_from_current_process(SymbolTable *st)
+{
+    uint64_t base_addr = query_base_addr();
+    if (base_addr == -1)
+        return -1;
+    st->base_addr = base_addr;
+
+    char path[1<<10];
+    if (current_executable_path(path, sizeof(path)) < 0)
+        return -1;
+
+    char *exe_ptr;
+    int   exe_len;
+    exe_ptr = read_file(path, &exe_len);
+    if (exe_ptr == NULL)
+        return -1;
+
+    if (load_symbols_from_elf(exe_ptr, exe_len, st) < 0) {
+        free(exe_ptr);
+        return -1;
+    }
+
+    free(exe_ptr);
+    return 0;
+}
+
+static void symbol_table_free(SymbolTable *st)
+{
+    free(st->symbols);
+}
+
+static char *symbol_table_find(SymbolTable *st, uint64_t addr)
+{
+    for (int i = 0; i < st->count; i++) {
+        Elf64_Sym *sym = (Elf64_Sym*) st->symbols + i;
+
+        if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+            continue;
+
+        if (sym->st_value == 0)
+            continue;
+
+        uint64_t sym_beg = st->base_addr + sym->st_value;
+        uint64_t sym_end = st->base_addr + sym->st_value + sym->st_size;
+
+        if (addr >= sym_beg && addr < sym_end)
+            return (char*) st->strings + sym->st_name;
+    }
+
+    return NULL;
+}
+
+#if 0
+static void symbol_table_dump(SymbolTable *st)
+{
+    for (int i = 0; i < st->count; i++) {
+        Elf64_Sym *sym = (Elf64_Sym*) st->symbols + i;
+
+        if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+            continue;
+
+        if (sym->st_value == 0)
+            continue;
+
+        char *name = (char*) st->strings + sym->st_name;
+        printf("%s\n", name);
+    }
+}
+#endif
+
+typedef struct {
+    char    *name;
+    uint64_t addr;
+} StackFrame;
+
+static int walk_stack(uint64_t rip, uint64_t rbp, SymbolTable *st, StackFrame *frames, int max_frames)
+{
+    int frame_count = 0;
+
+    if (frame_count < max_frames) {
+        frames[frame_count].addr = rip - st->base_addr;
+        frames[frame_count].name = symbol_table_find(st, rip);
+        frame_count++;
+    }
+
+    while (rbp != 0) {
+
+        if (rbp & 0xF)
+            break;
+
+        uint64_t *frame_ptr = (uint64_t*) rbp;
+
+        uint64_t next_rbp    = frame_ptr[0];
+        uint64_t return_addr = frame_ptr[1];
+
+        if (next_rbp != 0 && next_rbp <= rbp)
+            break;
+
+        if (return_addr == 0)
+            break;
+
+        if (frame_count == max_frames)
+            break;
+        frames[frame_count].addr = return_addr - st->base_addr;
+        frames[frame_count].name = symbol_table_find(st, return_addr);
+        frame_count++;
+
+        rbp = next_rbp;
+    }
+
+    return frame_count;
+}
+
+static bool        crash_logger_symbol_init = false;
+static char*       crash_logger_file_name = NULL;
+static SymbolTable crash_logger_symbol_table;
+static char*       crash_logger_signal_stack;
+
+static void crash_handler(int sig, siginfo_t *info, void *ucontext)
+{
+    if (crash_logger_symbol_init) {
+
+        // Buffer for evaluating format strings
+        char tmp[1<<9];
+        int len;
+
+        ucontext_t *ctx = (ucontext_t*) ucontext;
+        uint64_t rip = ctx->uc_mcontext.gregs[REG_RIP];
+        uint64_t rbp = ctx->uc_mcontext.gregs[REG_RBP];
+
+        StackFrame frames[64];
+        int count = walk_stack(rip, rbp, &crash_logger_symbol_table, frames, 64);
+
+        int fd = open(crash_logger_file_name, O_WRONLY | O_CREAT, 0666);
+        if (fd < 0)
+            exit(1);
+
+        CWEB_String sig_name = {0};
+        switch (sig) {
+            case SIGSEGV: sig_name = CWEB_STR("Segmentation fault");       break;
+            case SIGBUS : sig_name = CWEB_STR("Bus error");                break;
+            case SIGILL : sig_name = CWEB_STR("Illegal instruction");      break;
+            case SIGFPE : sig_name = CWEB_STR("Floating point exception"); break;
+            case SIGTRAP: sig_name = CWEB_STR("Trace trap");               break;
+            case SIGSYS : sig_name = CWEB_STR("Bad system call");          break;
+            case SIGABRT: sig_name = CWEB_STR("Abort");                    break;
+        }
+        if (sig_name.len == 0) {
+            len = snprintf(tmp, sizeof(tmp), "(unknown signal %d)\n", sig);
+            write(fd, tmp, len);
+        } else {
+            write(fd, sig_name.ptr, sig_name.len);
+            write(fd, "\n", 1);
+        }
+
+        for (int i = 0; i < count; i++) {
+            len = snprintf(tmp, sizeof(tmp), "  [%d] 0x%lx %s\n", i, frames[i].addr, 
+                frames[i].name ? frames[i].name : "?");
+            write(fd, tmp, len);
+        }
+
+        close(fd);
+    }
+    exit(1);
+}
+
+static int crash_logger_init(char *file_name, int file_name_len)
+{
+    {
+        char *file_name_copy = malloc(file_name_len + 1);
+        if (file_name_copy == NULL)
+            return -1;
+        memcpy(file_name_copy, file_name, file_name_len);
+        file_name_copy[file_name_len] = '\0';
+        crash_logger_file_name = file_name_copy;
+    }
+
+    if (symbol_table_from_current_process(&crash_logger_symbol_table) < 0) {
+        free(crash_logger_file_name);
+        return -1;
+    }
+
+    // Set up alternate signal stack
+    {
+        crash_logger_signal_stack = malloc(SIGSTKSZ);
+        if (crash_logger_signal_stack == NULL) {
+            symbol_table_free(&crash_logger_symbol_table);
+            free(crash_logger_file_name);
+            return -1;
+        }
+
+        stack_t ss;
+        ss.ss_sp = crash_logger_signal_stack;
+        ss.ss_size = SIGSTKSZ;
+        ss.ss_flags = 0;
+        if (sigaltstack(&ss, NULL) < 0) {
+            free(crash_logger_signal_stack);
+            symbol_table_free(&crash_logger_symbol_table);
+            free(crash_logger_file_name);
+            return -1;
+        }
+    }
+
+    {
+        // Register the crash handler
+        struct sigaction sa;
+        sa.sa_sigaction = crash_handler;
+        sa.sa_flags = SA_SIGINFO | SA_ONSTACK;  // Add SA_ONSTACK flag
+        sigemptyset(&sa.sa_mask);
+
+        // Memory errors
+        sigaction(SIGSEGV, &sa, NULL);  // Segmentation fault (invalid memory access)
+        sigaction(SIGBUS, &sa, NULL);   // Bus error (misaligned access, hardware error)
+
+        // Execution errors
+        sigaction(SIGILL, &sa, NULL);   // Illegal instruction
+        sigaction(SIGFPE, &sa, NULL);   // Floating point exception
+        sigaction(SIGTRAP, &sa, NULL);  // Trace trap
+
+        // System/resource errors
+        sigaction(SIGSYS, &sa, NULL);   // Bad system call
+        sigaction(SIGABRT, &sa, NULL);  // Abort (from assert, abort(), etc.)
+
+        // Optional: Resource limit violations
+        sigaction(SIGXCPU, &sa, NULL);  // CPU time limit exceeded
+        sigaction(SIGXFSZ, &sa, NULL);  // File size limit exceeded
+    }
+
+    crash_logger_symbol_init = true;
+    return 0;
+}
+
+static void crash_logger_free(void)
+{
+    if (!crash_logger_symbol_init)
+        return;
+
+    free(crash_logger_signal_stack);
+    symbol_table_free(&crash_logger_symbol_table);
+    free(crash_logger_file_name);
+
+    crash_logger_symbol_init = false;
+}
+
+#else
+
+static int crash_logger_init(char *file_name, int file_name_len)
+{
+    (void) file_name;
+    (void) file_name_len;
+    return -1;
+}
+
+static void crash_logger_free(void)
+{
+}
+
+#endif

src/main.h

@@ -221,6 +221,8 @@ typedef struct CWEB_Request CWEB_Request;
 int  cweb_global_init(void);
 void cweb_global_free(void);
 
+void cweb_enable_crash_logger(CWEB_String file);
+
 // TODO: comment
 CWEB *cweb_init(CWEB_String addr, uint16_t port, uint16_t secure_port,
     CWEB_String cert_key, CWEB_String private_key);