From 14b5368e7c0e1de48d71b26ece3734303dc48e74 Mon Sep 17 00:00:00 2001
From: kamkow1 <ikamileq@gmail.com>
Date: Wed, 12 Mar 2025 20:31:27 +0100
Subject: [PATCH] Print source on breakpoint hit

---
 debugus.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/debugus.c b/debugus.c
index 93d5b3b..0610aee 100644
--- a/debugus.c
+++ b/debugus.c
@@ -9,6 +9,7 @@
 #include <string.h>
 #include <errno.h>
 #include <signal.h>
+#include <time.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <sys/ptrace.h>
@@ -22,6 +23,27 @@
 #include "da.h"
 #include "libelfin_wrap.h"
 
+
+// They took my usleep() away >;( fuck u POSIX
+int msleep(long msec)
+{
+    struct timespec  ts;
+    int res;
+
+    if (msec < 0) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    ts.tv_sec = msec/1000;
+    ts.tv_nsec = (msec%1000) * 1000000;
+
+    do {
+        res = nanosleep(&ts, &ts);
+    } while(res && errno == EINTR);
+    return res;
+}
+
 #define LOG_ERR(fmt, ...) fprintf(stderr, "Error: " fmt, ##__VA_ARGS__)
 #define LOG_INF(fmt, ...) fprintf(stdout, "Info:  " fmt, ##__VA_ARGS__)
 
@@ -197,6 +219,46 @@ void dbg_handle_sigsegv(Dbg *dbg, siginfo_t info)
     }
 }
 
+void print_source(const char *file, size_t line)
+{
+    FILE *src = fopen(file, "r");
+    if (src == NULL) {
+        LOG_ERR("No source file found\n");
+        return;
+    }
+    fseek(src, 0L, SEEK_END);
+    long sz = ftell(src);
+    rewind(src);
+    
+    char *srcbuf = malloc(sz+1);
+    fread(srcbuf, sz, 1, src);
+    srcbuf[sz] = '\0';                    
+
+    char *p = srcbuf;
+    size_t i = 0;
+    while (p) {
+        char *next = strchr(p, '\n');
+        if (next) {
+            *next = '\0';
+        }
+
+        if (i == line) {
+            LOG_INF("Source:\n");
+            printf("%6zu %s\n", line, p);
+        }
+
+        if (next) {
+            *next = '\n';
+        }
+
+        p = next ? (next + 1) : NULL;
+        i++;
+    }
+
+    free(srcbuf);
+    fclose(src);
+}
+
 void dbg_handle_sigtrap(Dbg *dbg, siginfo_t info)
 {
     void dbg_set_rip(Dbg *dbg, uint64_t v);
@@ -211,6 +273,7 @@ void dbg_handle_sigtrap(Dbg *dbg, siginfo_t info)
             ai = libelfin_wrap_info_from_rip(dbg->plibelfin, dbg_get_rip(dbg) - (uint64_t)dbg->program_load_offset);
             if (ai != NULL) {
                 LOG_INF("Hit breakpoint at 0x%"PRIxPTR", %s:%zu\n", dbg_get_rip(dbg), ai->file, (size_t)ai->line);
+                print_source(ai->file, (size_t)ai->line);
                 libelfin_wrap_free_info(ai);
             } else {
                 LOG_INF("Hit breakpoint at 0x%"PRIxPTR"\n", dbg_get_rip(dbg));
@@ -593,6 +656,10 @@ void dbg_init_js(Dbg *dbg)
 
 void dbg_init_load_offset(Dbg *dbg)
 {
+    msleep(500); // We need to sleep for a bit, because we need to ensure that our debuggee
+                 // program has already been loaded into memory. This is technically a bad
+                 // practice since we're sleeping for 500ms and praying that it's enough
+                 // time to ensure that debuggee has been loaded, but if it works, it works.
     procmaps_iterator maps_iter = {0};
     procmaps_error_t parser_err = PROCMAPS_SUCCESS;