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MDEV-23491: __bss_start breaks compilation of various platforms

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Remove __bss_start & Co, because systen call "write" check buffer address and return EFAULT if it is wrong.
This commit is contained in:
Oleksandr Byelkin
2020-08-16 22:14:59 +02:00
parent 5796021174
commit ece0b0623c
3 changed files with 84 additions and 107 deletions
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122
mysys/stacktrace.c
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@@ -34,107 +34,16 @@
#include <execinfo.h>
#endif
#ifdef __linux__
#define PTR_SANE(p) ((p) && (char*)(p) >= heap_start && (char*)(p) <= heap_end)
static char *heap_start;
char *__bss_start;
#else
#define PTR_SANE(p) (p)
#endif /* __linux */
void my_init_stacktrace()
{
#ifdef __linux__
heap_start = (char*) &__bss_start;
#endif /* __linux__ */
}
#ifdef __linux__
static void print_buffer(char *buffer, size_t count)
{
const char s[]= " ";
for (; count && *buffer; --count)
{
my_write_stderr(isprint(*buffer) ? buffer : s, 1);
++buffer;
}
}
/**
Access the pages of this process through /proc/self/task/<tid>/mem
in order to safely print the contents of a memory address range.
@param addr The address at the start of the memory region.
@param max_len The length of the memory region.
@return Zero on success.
*/
static int safe_print_str(const char *addr, int max_len)
{
int fd;
pid_t tid;
off_t offset;
ssize_t nbytes= 0;
size_t total, count;
char buf[256];
tid= (pid_t) syscall(SYS_gettid);
sprintf(buf, "/proc/self/task/%d/mem", tid);
if ((fd= open(buf, O_RDONLY)) < 0)
return -1;
/* Ensure that off_t can hold a pointer. */
compile_time_assert(sizeof(off_t) >= sizeof(intptr));
total= max_len;
offset= (intptr) addr;
/* Read up to the maximum number of bytes. */
while (total)
{
count= MY_MIN(sizeof(buf), total);
if ((nbytes= pread(fd, buf, count, offset)) < 0)
{
/* Just in case... */
if (errno == EINTR)
continue;
else
break;
}
/* Advance offset into memory. */
total-= nbytes;
offset+= nbytes;
addr+= nbytes;
/* Output the printable characters. */
print_buffer(buf, nbytes);
/* Break if less than requested... */
if ((count - nbytes))
break;
}
if (nbytes == -1)
my_safe_printf_stderr("Can't read from address %p", addr);
close(fd);
return 0;
}
#endif
/*
Attempt to print a char * pointer as a string.
SYNOPSIS
Prints either until the end of string ('\0'), or max_len characters have
been printed.
Prints until max_len characters have been printed.
RETURN VALUE
0 Pointer was within the heap address space.
@@ -149,24 +58,25 @@ static int safe_print_str(const char *addr, int max_len)
int my_safe_print_str(const char* val, int max_len)
{
#ifdef __linux__
char *heap_end;
// Try and make use of /proc filesystem to safely print memory contents.
if (!safe_print_str(val, max_len))
return 0;
heap_end= (char*) sbrk(0);
#endif
if (!PTR_SANE(val))
const char *orig_val= val;
if (!val)
{
my_safe_printf_stderr("%s", "is an invalid pointer");
my_safe_printf_stderr("%s", "(null)");
return 1;
}
for (; max_len && PTR_SANE(val) && *val; --max_len)
my_write_stderr((val++), 1);
for (; max_len; --max_len)
{
if (my_write_stderr((val++), 1) != 1)
{
if ((errno == EFAULT) &&(val == orig_val + 1))
{
// We can not read the address from very beginning
my_safe_printf_stderr("Can't access address %p", orig_val);
}
break;
}
}
my_safe_printf_stderr("%s", "\n");
return 0;