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| author |   espie <espie@openbsd.org> | 1999-09-28 22:17:51 +0000 |
|---|---|---|
| committer | espie <espie@openbsd.org> | 1999-09-28 22:17:51 +0000 |
| commit | abff55a67efe62b2f792c5ec2201f12036b92c78 (patch) | |
| tree | de3fb43bf8ee788f88b1a3b6f2454590935b9a48 /lib/libc/stdio/fopen.3 | |
| parent | Fix (diff) | |
| download | wireguard-openbsd-abff55a67efe62b2f792c5ec2201f12036b92c78.tar.xz wireguard-openbsd-abff55a67efe62b2f792c5ec2201f12036b92c78.zip | |
Nail down semantics in case of failure.
example for fdopen.
Diffstat (limited to 'lib/libc/stdio/fopen.3')
| -rw-r--r-- | lib/libc/stdio/fopen.3 | 33 |
1 files changed, 31 insertions, 2 deletions
diff --git a/lib/libc/stdio/fopen.3 b/lib/libc/stdio/fopen.3 index 15f281a297f..c04c6305b04 100644 --- a/lib/libc/stdio/fopen.3 +++ b/lib/libc/stdio/fopen.3 @@ -1,4 +1,4 @@ -.\" $OpenBSD: fopen.3,v 1.6 1999/09/26 14:54:10 espie Exp $ +.\" $OpenBSD: fopen.3,v 1.7 1999/09/28 22:17:51 espie Exp $ .\" .\" Copyright (c) 1990, 1991, 1993 .\" The Regents of the University of California. All rights reserved. @@ -126,6 +126,11 @@ function associates a stream with the existing file descriptor The .Fa mode of the stream must be compatible with the mode of the file descriptor. +If +.Fn fdopen +fails, the file descriptor +.Fa fildes +is not affected in any way. .Pp The .Fn freopen @@ -135,7 +140,9 @@ opens the file whose name is the string pointed to by and associates the stream pointed to by .Fa stream with it. -The original stream (if it exists) is closed. +The original stream (if it exists) is always closed, even if +.Fn freopen +fails. The .Fa mode argument is used just as in the @@ -232,3 +239,25 @@ The function conforms to .St -p1003.1-88 . +.Sh CAVEATS +Proper code using +.Fn fdopen +with error checking should +.Xr close 2 +.Fa fildes +in case of failure, and +.Xr fclose 3 +the resulting FILE * in case of success. +.Bd -literal + FILE *file; + int fd; + + if ((file = fdopen(fd)) != NULL) { + /* perform operations on the FILE * */ + fclose(file); + } else { + /* failure, report the error */ + close(fd); + } +.Ed + |