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gcore: Forward pending signals when detaching from the target.

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Otherwise gcore's ptrace attach operation can race with delivery of a
signal and cause it to be lost.

In collaboration with:	Suraj Raju <sraju@isilon.com>
Reviewed by:	bdrewery
Approved by:	re (gjb, kib)
MFC after:	2 weeks
Sponsored by:	EMC / Isilon Storage Division
This commit is contained in:
Mark Johnston 2016-06-24 20:21:32 +00:00
parent 8095b3c249
commit 0367ff567c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=302179
1 changed files with 13 additions and 3 deletions
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16
usr.bin/gcore/elfcore.c
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@ -126,6 +126,7 @@ static vm_map_entry_t readmap(pid_t);
static void *procstat_sysctl(void *, int, size_t, size_t *sizep);
static pid_t g_pid; /* Pid being dumped, global for elf_detach */
static int g_status; /* proc status after ptrace attach */
static int
elf_ident(int efd, pid_t pid __unused, char *binfile __unused)
@ -159,9 +160,18 @@ elf_ident(int efd, pid_t pid __unused, char *binfile __unused)
static void
elf_detach(void)
{
int sig;
if (g_pid != 0)
ptrace(PT_DETACH, g_pid, (caddr_t)1, 0);
if (g_pid != 0) {
/*
* Forward any pending signals. SIGSTOP is generated by ptrace
* itself, so ignore it.
*/
sig = WIFSTOPPED(g_status) ? WSTOPSIG(g_status) : 0;
if (sig == SIGSTOP)
sig = 0;
ptrace(PT_DETACH, g_pid, (caddr_t)1, sig);
}
}
/*
@ -187,7 +197,7 @@ elf_coredump(int efd __unused, int fd, pid_t pid)
ptrace(PT_ATTACH, pid, NULL, 0);
if (errno)
err(1, "PT_ATTACH");
if (waitpid(pid, NULL, 0) == -1)
if (waitpid(pid, &g_status, 0) == -1)
err(1, "waitpid");
/* Get the program's memory map. */