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core: be more careful when inheriting stdout fds to stderr

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We need to compare the fd name/file name if we inherit an fd from stdout
to stderr. Let's do that.

Fixes: #10875
This commit is contained in:
Lennart Poettering 2018-11-26 21:07:48 +01:00
parent 8d33232ef1
commit 41fc585a7a
1 changed files with 25 additions and 2 deletions
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27
src/core/execute.c
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@ -544,6 +544,30 @@ static int setup_input(
}
}
static bool can_inherit_stderr_from_stdout(
const ExecContext *context,
ExecOutput o,
ExecOutput e) {
assert(context);
/* Returns true, if given the specified STDERR and STDOUT output we can directly dup() the stdout fd to the
* stderr fd */
if (e == EXEC_OUTPUT_INHERIT)
return true;
if (e != o)
return false;
if (e == EXEC_OUTPUT_NAMED_FD)
return streq_ptr(context->stdio_fdname[STDOUT_FILENO], context->stdio_fdname[STDERR_FILENO]);
if (IN_SET(e, EXEC_OUTPUT_FILE, EXEC_OUTPUT_FILE_APPEND))
return streq_ptr(context->stdio_file[STDOUT_FILENO], context->stdio_file[STDERR_FILENO]);
return true;
}
static int setup_output(
const Unit *unit,
const ExecContext *context,
@ -602,7 +626,7 @@ static int setup_output(
return fileno;
/* Duplicate from stdout if possible */
if ((e == o && e != EXEC_OUTPUT_NAMED_FD) || e == EXEC_OUTPUT_INHERIT)
if (can_inherit_stderr_from_stdout(context, o, e))
return dup2(STDOUT_FILENO, fileno) < 0 ? -errno : fileno;
o = e;
@ -693,7 +717,6 @@ static int setup_output(
flags |= O_APPEND;
fd = acquire_path(context->stdio_file[fileno], flags, 0666 & ~context->umask);
if (fd < 0)
return fd;