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libspl/backtrace: helper macros for output

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My eyes are going blurry looking at all those write calls. This is much
nicer.

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Close #16653
This commit is contained in:
Rob Norris 2024-10-18 13:49:41 +11:00 committed by Brian Behlendorf
parent 0a001f3088
commit c7e47b3d9a
1 changed files with 31 additions and 27 deletions
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58
lib/libspl/backtrace.c
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@ -25,12 +25,20 @@
#include <sys/backtrace.h>
#include <sys/types.h>
#include <sys/debug.h>
#include <unistd.h>
/*
* libspl_backtrace() must be safe to call from inside a signal hander. This
* mostly means it must not allocate, and so we can't use things like printf.
* Output helpers. libspl_backtrace() must not block, must be thread-safe and
* must be safe to call from a signal handler. At least, that means not having
* printf, so we end up having to call write() directly on the fd. That's
* awkward, as we always have to pass through a length, and some systems will
* complain if we don't consume the return. So we have some macros to make
* things a little more palatable.
*/
#define spl_bt_write_n(fd, s, n) \
do { ssize_t r __maybe_unused = write(fd, s, n); } while (0)
#define spl_bt_write(fd, s) spl_bt_write_n(fd, s, sizeof (s))
#if defined(HAVE_LIBUNWIND)
#define UNW_LOCAL_ONLY
@ -62,7 +70,6 @@ libspl_u64_to_hex_str(uint64_t v, size_t digits, char *buf, size_t buflen)
void
libspl_backtrace(int fd)
{
ssize_t ret __attribute__((unused));
unw_context_t uc;
unw_cursor_t cp;
unw_word_t v;
@ -72,7 +79,7 @@ libspl_backtrace(int fd)
unw_getcontext(&uc);
unw_init_local(&cp, &uc);
ret = write(fd, "Registers:\n", 11);
spl_bt_write(fd, "Registers:\n");
c = 0;
for (uint_t regnum = 0; regnum <= UNW_TDEP_LAST_REG; regnum++) {
if (unw_get_reg(&cp, regnum, &v) < 0)
@ -85,42 +92,42 @@ libspl_backtrace(int fd)
&buf[1], sizeof (buf)-1) + 1;
name = buf;
}
ret = write(fd, " ", 5-MIN(n, 3));
ret = write(fd, name, n);
ret = write(fd, ": 0x", 4);
spl_bt_write_n(fd, " ", 5-MIN(n, 3));
spl_bt_write_n(fd, name, n);
spl_bt_write(fd, ": 0x");
n = libspl_u64_to_hex_str(v, 18, buf, sizeof (buf));
ret = write(fd, buf, n);
spl_bt_write_n(fd, buf, n);
if (!(++c % 3))
ret = write(fd, "\n", 1);
spl_bt_write(fd, "\n");
}
if (c % 3)
ret = write(fd, "\n", 1);
spl_bt_write(fd, "\n");
unw_init_local(&cp, &uc);
ret = write(fd, "Call trace:\n", 12);
spl_bt_write(fd, "Call trace:\n");
while (unw_step(&cp) > 0) {
unw_get_reg(&cp, UNW_REG_IP, &v);
ret = write(fd, " [0x", 5);
spl_bt_write(fd, " [0x");
n = libspl_u64_to_hex_str(v, 18, buf, sizeof (buf));
ret = write(fd, buf, n);
ret = write(fd, "] ", 2);
spl_bt_write_n(fd, buf, n);
spl_bt_write(fd, "] ");
unw_get_proc_name(&cp, buf, sizeof (buf), &v);
for (n = 0; n < sizeof (buf) && buf[n] != '\0'; n++) {}
ret = write(fd, buf, n);
ret = write(fd, "+0x", 3);
spl_bt_write_n(fd, buf, n);
spl_bt_write(fd, "+0x");
n = libspl_u64_to_hex_str(v, 2, buf, sizeof (buf));
ret = write(fd, buf, n);
spl_bt_write_n(fd, buf, n);
#ifdef HAVE_LIBUNWIND_ELF
ret = write(fd, " (in ", 5);
spl_bt_write(fd, " (in ");
unw_get_elf_filename(&cp, buf, sizeof (buf), &v);
for (n = 0; n < sizeof (buf) && buf[n] != '\0'; n++) {}
ret = write(fd, buf, n);
ret = write(fd, " +0x", 4);
spl_bt_write_n(fd, buf, n);
spl_bt_write(fd, " +0x");
n = libspl_u64_to_hex_str(v, 2, buf, sizeof (buf));
ret = write(fd, buf, n);
ret = write(fd, ")", 1);
spl_bt_write_n(fd, buf, n);
spl_bt_write(fd, ")");
#endif
ret = write(fd, "\n", 1);
spl_bt_write(fd, "\n");
}
}
#elif defined(HAVE_BACKTRACE)
@ -129,15 +136,12 @@ libspl_backtrace(int fd)
void
libspl_backtrace(int fd)
{
ssize_t ret __attribute__((unused));
void *btptrs[64];
size_t nptrs = backtrace(btptrs, 64);
ret = write(fd, "Call trace:\n", 12);
spl_bt_write(fd, "Call trace:\n");
backtrace_symbols_fd(btptrs, nptrs, fd);
}
#else
#include <sys/debug.h>
void
libspl_backtrace(int fd __maybe_unused)
{