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Fixed my_addr_resolve

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When a server is compiled with -fPIE, my_addr_resolve needs to subtract the info.dli_fbase from symbol addresses in memory for addr2line to recognize them.
When a server is compiled without -fPIE, my_addr_resolve should not do it.
Unfortunately not all compilers define __PIE__ when -fPIE was used
(e.g. older gcc doesn't), so we have to resort to run-time detection.
This commit is contained in:
Monty 2020-08-17 19:01:43 +03:00 • committed by Sergei Golubchik
parent 942a5a89a9
commit a93c514595
1 changed files with 17 additions and 5 deletions
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22
mysys/my_addr_resolve.c
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@ -170,6 +170,7 @@ static pid_t pid;
static char addr2line_binary[1024]; static char addr2line_binary[1024];
static char output[1024]; static char output[1024];
static struct pollfd poll_fds; static struct pollfd poll_fds;
static void *addr_offset;
int start_addr2line_fork(const char *binary_path) int start_addr2line_fork(const char *binary_path)
{ {
@ -297,7 +298,6 @@ static int addr_resolve(void *ptr, my_addr_loc *loc)
int my_addr_resolve(void *ptr, my_addr_loc *loc) int my_addr_resolve(void *ptr, my_addr_loc *loc)
{ {
Dl_info info; Dl_info info;
int error;
if (!dladdr(ptr, &info)) if (!dladdr(ptr, &info))
return 1; return 1;
@ -307,7 +307,7 @@ int my_addr_resolve(void *ptr, my_addr_loc *loc)
/* /*
We use dli_fname in case the path is longer than the length of We use dli_fname in case the path is longer than the length of
our static string. We don't want to allocate anything our static string. We don't want to allocate anything
dynamicaly here as we are in a "crashed" state. dynamically here as we are in a "crashed" state.
*/ */
if (start_addr2line_fork(info.dli_fname)) if (start_addr2line_fork(info.dli_fname))
{ {
@ -318,10 +318,22 @@ int my_addr_resolve(void *ptr, my_addr_loc *loc)
} }
/* Save result for future comparisons. */ /* Save result for future comparisons. */
strnmov(addr2line_binary, info.dli_fname, sizeof(addr2line_binary)); strnmov(addr2line_binary, info.dli_fname, sizeof(addr2line_binary));
/*
Check if we should use info.dli_fbase as an offset or not
for the base program. This is depending on if the compilation is
done with PIE or not.
*/
addr_offset= info.dli_fbase;
#ifndef __PIE__
if (strcmp(info.dli_fname, my_progname) == 0 &&
addr_resolve((void*) my_addr_resolve, loc) == 0 &&
strcmp(loc->func, "my_addr_resolve") == 0)
addr_offset= 0;
#endif
} }
if (!(error= addr_resolve((void*) (ptr - info.dli_fbase), loc)))
return 0; return addr_resolve((void*) (ptr - addr_offset), loc);
return error;
} }