path: root/src/signal/psignal.c
diff options
authorRich Felker <>2018-08-30 00:00:22 -0400
committerRich Felker <>2018-08-30 00:05:52 -0400
commitcd8d8309975893736fe03e10b72de9678c5784fb (patch)
tree858d5561059f704f1837d46bc83873c2491c9fd8 /src/signal/psignal.c
parenta43a7b215cf7b71d1371c63927c17bae7177aa95 (diff)
prevent psignal/psiginfo from clobbering stderr orientation, errno
these functions are specified to write to stderr but not set its orientation, presumably so that they can be used in programs operating stderr in wide mode. also, they are not allowed to clobber errno on success. save and restore to meet the requirement. psiginfo is reduced to a think wrapper around psignal, since it already behaved the same. if we want to add more detailed siginfo printing at some point this will need refactoring.
Diffstat (limited to 'src/signal/psignal.c')
1 files changed, 20 insertions, 3 deletions
diff --git a/src/signal/psignal.c b/src/signal/psignal.c
index 02f1c760..138dbe00 100644
--- a/src/signal/psignal.c
+++ b/src/signal/psignal.c
@@ -1,10 +1,27 @@
-#include <stdio.h>
+#include "stdio_impl.h"
#include <string.h>
#include <signal.h>
+#include <errno.h>
void psignal(int sig, const char *msg)
+ FILE *f = stderr;
char *s = strsignal(sig);
- if (msg) fprintf(stderr, "%s: %s\n", msg, s);
- else fprintf(stderr, "%s\n", s);
+ FLOCK(f);
+ /* Save stderr's orientation and encoding rule, since psignal is not
+ * permitted to change them. Save errno and restore it if there is no
+ * error since fprintf might change it even on success but psignal is
+ * not permitted to do so. */
+ void *old_locale = f->locale;
+ int old_mode = f->mode;
+ int old_errno = errno;
+ if (fprintf(f, "%s%s%s\n", msg?msg:"", msg?": ":"", s)>=0)
+ errno = old_errno;
+ f->mode = old_mode;
+ f->locale = old_locale;