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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-06-26 16:18:37 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-06-26 16:18:37 +0000
commitb6b00dd55e035bfbe311a527b567962ffa77ee43 (patch)
treecafc4d13785448e5a78bd40a51697ee07f07ac12 /lib/write_full.c
parentAdding debian version 1:4.13+dfsg1-5. (diff)
downloadshadow-b6b00dd55e035bfbe311a527b567962ffa77ee43.tar.xz
shadow-b6b00dd55e035bfbe311a527b567962ffa77ee43.zip
Merging upstream version 1:4.15.2.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/write_full.c')
-rw-r--r--lib/write_full.c77
1 files changed, 77 insertions, 0 deletions
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+/*
+ * SPDX-FileCopyrightText: 2023, Christian Göttsche <cgzones@googlemail.com>
+ * SPDX-FileCopyrightText: 2023, Alejandro Colomar <alx@kernel.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <errno.h>
+#include <unistd.h>
+
+#include "prototypes.h"
+
+
+/*
+ * SYNOPSIS
+ * int write_full(int fd, const void *buf, size_t count);
+ *
+ * ARGUMENTS
+ * fd File descriptor.
+ * buf Source buffer to write(2) into 'fd'.
+ * count Size of 'buf'.
+ *
+ * DESCRIPTION
+ * Write 'count' bytes from the buffer starting at 'buf' to the
+ * file referred to by 'fd'.
+ *
+ * This function is similar to write(2), except that it retries
+ * in case of a short write.
+ *
+ * Since this function either performs a full write, or fails, the
+ * return value is simpler than for write(2).
+ *
+ * RETURN VALUE
+ * 0 On success.
+ * -1 On error.
+ *
+ * ERRORS
+ * See write(2).
+ *
+ * CAVEATS
+ * This function can still perform partial writes: if the function
+ * fails in the loop after one or more write(2) calls have
+ * succeeded, it will report a failure, but some data may have been
+ * written. In such a case, it's the caller's responsibility to
+ * make sure that the partial write is not problematic, and
+ * remediate it if it is --maybe by trying to remove the file--.
+ */
+
+
+int
+write_full(int fd, const void *buf, size_t count)
+{
+ ssize_t w;
+ const unsigned char *p;
+
+ p = buf;
+
+ while (count > 0) {
+ w = write(fd, p, count);
+ if (w == -1) {
+ if (errno == EINTR)
+ continue;
+
+ return -1;
+ }
+
+ p += w;
+ count -= w;
+ }
+
+ return 0;
+}