ash: add more checks to forkshell debug

Rearrange the handling of pointer relocation during forkshell and
add a couple of additional sanity checks.  There's no functional
change to non-debug builds.

1 files changed, 36 insertions, 15 deletions

diff --git a/shell/ash.c b/shell/ash.c
index e45c8d61d..90f4c9773 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9844,6 +9844,7 @@ static char *funcstring_end;    /* end of block to allocate strings from */
 static int fs_size;
 # if FORKSHELL_DEBUG
 static void *fs_start;
+static void *fs_funcstring;
 static const char **annot;
 # endif
 #endif
@@ -9995,36 +9996,55 @@ static union node *copynode(union node *);
 # if FORKSHELL_DEBUG
 #  define FREE 1
 #  define NO_FREE 2
-#  define ANNOT(dst,note) { \
-                if (annot) \
-                        annot[(char *)&dst - (char *)fs_start] = note; \
-        }
+#  define MARK_PTR(dst,note,flag) forkshell_mark_ptr((void *)&dst, note, flag)
 # else
 #  define FREE 1
 #  define NO_FREE 1
-#  define ANNOT(dst,note)
+#  define MARK_PTR(dst,note,flag) forkshell_mark_ptr((void *)&dst, flag)
 # endif
 
-/* The relocation map is offset from the start of the forkshell data
- * block by 'fs_size' bytes.  The flag relating to a particular destination
- * pointer is thus at (dst+fs_size). */
-# define MARK_PTR(dst,flag) {*((char *)&dst + fs_size) = flag;}
+#if FORKSHELL_DEBUG
+static void forkshell_mark_ptr(void *dst, const char *note, int flag)
+#else
+static void forkshell_mark_ptr(void *dst, int flag)
+#endif
+{
+        /* The relocation map is offset from the start of the forkshell data
+         * block by 'fs_size' bytes.  The flag relating to a particular
+         * destination pointer is thus at (dst+fs_size). */
+        *((char *)dst + fs_size) = flag;
+
+#if FORKSHELL_DEBUG
+        if (dst < fs_start || dst >= fs_funcstring) {
+                fprintf(stderr, "dst (%p) out of range (%p %p)\n",
+                                dst, fs_start, fs_funcstring);
+        }
+        if (annot) {
+                if (annot[(char *)dst - (char *)fs_start]) {
+                        fprintf(stderr, "duplicate annotation: %s %s\n",
+                                                annot[(char *)dst - (char *)fs_start], note);
+                }
+                annot[(char *)dst - (char *)fs_start] = note;
+        }
+#endif
+}
 
 # define SAVE_PTR(dst,note,flag) { \
         if (fs_size) { \
-                MARK_PTR(dst,flag); ANNOT(dst,note); \
+                MARK_PTR(dst,note,flag); \
         } \
 }
 # define SAVE_PTR2(dst1,note1,flag1,dst2,note2,flag2) { \
         if (fs_size) { \
-                MARK_PTR(dst1,flag1); MARK_PTR(dst2,flag2); \
-                ANNOT(dst1,note1); ANNOT(dst2,note2); \
+                MARK_PTR(dst1,note1,flag1); \
+                MARK_PTR(dst2,note2,flag2); \
         } \
 }
 # define SAVE_PTR3(dst1,note1,flag1,dst2,note2,flag2,dst3,note3,flag3) { \
         if (fs_size) { \
-                MARK_PTR(dst1,flag1); MARK_PTR(dst2,flag2); MARK_PTR(dst3,flag3); \
-                ANNOT(dst1,note1); ANNOT(dst2,note2); ANNOT(dst3,note3); \
+                MARK_PTR(dst1,note1,flag1); \
+                MARK_PTR(dst2,note2,flag2); \
+                MARK_PTR(dst3,note3,flag3); \
         } \
 }
 #else
@@ -16522,7 +16542,7 @@ spawn_forkshell(struct forkshell *fs, struct job *jp, union node *n, int mode)
 #undef SAVE_PTR
 #undef SAVE_PTR2
 #undef SAVE_PTR3
-#define SAVE_PTR(dst,note,flag) {MARK_PTR(dst,flag); ANNOT(dst,note);}
+#define SAVE_PTR(dst,note,flag) {MARK_PTR(dst,note,flag);}
 
 static int align_len(const char *s)
 {
@@ -17224,6 +17244,7 @@ forkshell_prepare(struct forkshell *fs)
         funcstring_end = (char *)new + size;
 #if FORKSHELL_DEBUG
         fs_start = new;
+        fs_funcstring = (char *)new + sizeof(struct forkshell) + ds.funcblocksize;
         relocate = (char *)new + size;
         annot = (const char **)xzalloc(sizeof(char *)*relocatesize);
 #endif