Jakub asked whether it would be possible to extend backtrace_syminfo to
work for variables as well as functions. It's a straightforward
extension, implemented by this patch. Bootstrapped and ran libbacktrace
tests on x86_64-unknown-linux-gnu. Any comments on this patch before I
submit it?
Ian
2013-11-15 Ian Lance Taylor <i...@google.com>
* backtrace.h (backtrace_syminfo): Update comment and parameter
name to take any address, not just a PC value.
* elf.c (STT_OBJECT): Define.
(elf_nosyms): Rename parameter pc to addr.
(elf_symbol_search): Rename local variable pc to addr.
(elf_initialize_syminfo): Add STT_OBJECT symbols to elf_symbols.
(elf_syminfo): Rename parameter pc to addr.
* btest.c (global): New global variable.
(test5): New test.
(main): Call test5.
Index: libbacktrace/elf.c
===================================================================
--- libbacktrace/elf.c (revision 204717)
+++ libbacktrace/elf.c (working copy)
@@ -101,6 +101,7 @@ dl_iterate_phdr (int (*callback) (struct
#undef SHT_SYMTAB
#undef SHT_STRTAB
#undef SHT_DYNSYM
+#undef STT_OBJECT
#undef STT_FUNC
/* Basic types. */
@@ -215,6 +216,7 @@ typedef struct
#endif /* BACKTRACE_ELF_SIZE != 32 */
+#define STT_OBJECT 1
#define STT_FUNC 2
/* An index of ELF sections we care about. */
@@ -293,7 +295,7 @@ elf_nodebug (struct backtrace_state *sta
static void
elf_nosyms (struct backtrace_state *state ATTRIBUTE_UNUSED,
- uintptr_t pc ATTRIBUTE_UNUSED,
+ uintptr_t addr ATTRIBUTE_UNUSED,
backtrace_syminfo_callback callback ATTRIBUTE_UNUSED,
backtrace_error_callback error_callback, void *data)
{
@@ -316,7 +318,7 @@ elf_symbol_compare (const void *v1, cons
return 0;
}
-/* Compare a PC against an elf_symbol for bsearch. We allocate one
+/* Compare an ADDR against an elf_symbol for bsearch. We allocate one
extra entry in the array so that this can look safely at the next
entry. */
@@ -325,12 +327,12 @@ elf_symbol_search (const void *vkey, con
{
const uintptr_t *key = (const uintptr_t *) vkey;
const struct elf_symbol *entry = (const struct elf_symbol *) ventry;
- uintptr_t pc;
+ uintptr_t addr;
- pc = *key;
- if (pc < entry->address)
+ addr = *key;
+ if (addr < entry->address)
return -1;
- else if (pc >= entry->address + entry->size)
+ else if (addr >= entry->address + entry->size)
return 1;
else
return 0;
@@ -360,7 +362,10 @@ elf_initialize_syminfo (struct backtrace
elf_symbol_count = 0;
for (i = 0; i < sym_count; ++i, ++sym)
{
- if ((sym->st_info & 0xf) == STT_FUNC)
+ int info;
+
+ info = sym->st_info & 0xf;
+ if (info == STT_FUNC || info == STT_OBJECT)
++elf_symbol_count;
}
@@ -375,7 +380,10 @@ elf_initialize_syminfo (struct backtrace
j = 0;
for (i = 0; i < sym_count; ++i, ++sym)
{
- if ((sym->st_info & 0xf) != STT_FUNC)
+ int info;
+
+ info = sym->st_info & 0xf;
+ if (info != STT_FUNC && info != STT_OBJECT)
continue;
if (sym->st_name >= strtab_size)
{
@@ -445,10 +453,10 @@ elf_add_syminfo_data (struct backtrace_s
}
}
-/* Return the symbol name and value for a PC. */
+/* Return the symbol name and value for an ADDR. */
static void
-elf_syminfo (struct backtrace_state *state, uintptr_t pc,
+elf_syminfo (struct backtrace_state *state, uintptr_t addr,
backtrace_syminfo_callback callback,
backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
void *data)
@@ -463,7 +471,7 @@ elf_syminfo (struct backtrace_state *sta
edata = edata->next)
{
sym = ((struct elf_symbol *)
- bsearch (&pc, edata->symbols, edata->count,
+ bsearch (&addr, edata->symbols, edata->count,
sizeof (struct elf_symbol), elf_symbol_search));
if (sym != NULL)
break;
@@ -485,7 +493,7 @@ elf_syminfo (struct backtrace_state *sta
break;
sym = ((struct elf_symbol *)
- bsearch (&pc, edata->symbols, edata->count,
+ bsearch (&addr, edata->symbols, edata->count,
sizeof (struct elf_symbol), elf_symbol_search));
if (sym != NULL)
break;
@@ -495,9 +503,9 @@ elf_syminfo (struct backtrace_state *sta
}
if (sym == NULL)
- callback (data, pc, NULL, 0);
+ callback (data, addr, NULL, 0);
else
- callback (data, pc, sym->name, sym->address);
+ callback (data, addr, sym->name, sym->address);
}
/* Add the backtrace data for one ELF file. */
Index: libbacktrace/btest.c
===================================================================
--- libbacktrace/btest.c (revision 204717)
+++ libbacktrace/btest.c (working copy)
@@ -598,6 +598,53 @@ f33 (int f1line, int f2line)
return failures;
}
+int global = 1;
+
+static int
+test5 (void)
+{
+ struct symdata symdata;
+ int i;
+
+ symdata.name = NULL;
+ symdata.val = 0;
+ symdata.failed = 0;
+
+ i = backtrace_syminfo (state, (uintptr_t) &global, callback_three,
+ error_callback_three, &symdata);
+ if (i == 0)
+ {
+ fprintf (stderr,
+ "test5: unexpected return value from backtrace_syminfo %d\n",
+ i);
+ symdata.failed = 1;
+ }
+
+ if (!symdata.failed)
+ {
+ if (symdata.name == NULL)
+ {
+ fprintf (stderr, "test5: NULL syminfo name\n");
+ symdata.failed = 1;
+ }
+ else if (strcmp (symdata.name, "global") != 0)
+ {
+ fprintf (stderr,
+ "test5: unexpected syminfo name got %s expected %s\n",
+ symdata.name, "global");
+ symdata.failed = 1;
+ }
+ }
+
+ printf ("%s: backtrace_syminfo variable\n",
+ symdata.failed ? "FAIL" : "PASS");
+
+ if (symdata.failed)
+ ++failures;
+
+ return failures;
+}
+
static void
error_callback_create (void *data ATTRIBUTE_UNUSED, const char *msg,
int errnum)
@@ -622,6 +669,7 @@ main (int argc ATTRIBUTE_UNUSED, char **
test2 ();
test3 ();
test4 ();
+ test5 ();
#endif
exit (failures ? EXIT_FAILURE : EXIT_SUCCESS);
Index: libbacktrace/backtrace.h
===================================================================
--- libbacktrace/backtrace.h (revision 204717)
+++ libbacktrace/backtrace.h (working copy)
@@ -177,17 +177,17 @@ typedef void (*backtrace_syminfo_callbac
const char *symname,
uintptr_t symval);
-/* Given PC, a program counter in the current program, call the
- callback information with the symbol name and value describing the
- function in which PC may be found. This will call either CALLBACK
- or ERROR_CALLBACK exactly once. This returns 1 on success, 0 on
- failure. This function requires the symbol table but does not
- require the debug info. Note that if the symbol table is present
- but PC could not be found in the table, CALLBACK will be called
- with a NULL SYMNAME argument. Returns 1 on success, 0 on
- error. */
+/* Given ADDR, an address or program counter in the current program,
+ call the callback information with the symbol name and value
+ describing the function or variable in which ADDR may be found.
+ This will call either CALLBACK or ERROR_CALLBACK exactly once.
+ This returns 1 on success, 0 on failure. This function requires
+ the symbol table but does not require the debug info. Note that if
+ the symbol table is present but ADDR could not be found in the
+ table, CALLBACK will be called with a NULL SYMNAME argument.
+ Returns 1 on success, 0 on error. */
-extern int backtrace_syminfo (struct backtrace_state *state, uintptr_t pc,
+extern int backtrace_syminfo (struct backtrace_state *state, uintptr_t addr,
backtrace_syminfo_callback callback,
backtrace_error_callback error_callback,
void *data);
