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authorMarkus F.X.J. Oberhumer <markus@oberhumer.com>2021-04-15 07:43:13 +0200
committerMarkus F.X.J. Oberhumer <markus@oberhumer.com>2021-04-15 07:43:13 +0200
commit68622a02adfa7ebd3a195667d3fbf8e1f10ca93f (patch)
tree8dd77202cd9cdbf5f59ae42dd3293d87fbabcfbb
parent1d8bbdc1a59fd5246ec60bc3db1ece055ef83639 (diff)
downloadbfs-68622a02adfa7ebd3a195667d3fbf8e1f10ca93f.tar.xz
util: introduce safe versions of read & write that handle interrupted
systems calls.
-rw-r--r--bar.c2
-rw-r--r--spawn.c11
-rw-r--r--util.c20
-rw-r--r--util.h10
4 files changed, 35 insertions, 8 deletions
diff --git a/bar.c b/bar.c
index e1e2857..67f5d6e 100644
--- a/bar.c
+++ b/bar.c
@@ -60,7 +60,7 @@ static int ass_puts(int fd, const char *str) {
size_t len = strlen(str);
while (len > 0) {
- ssize_t ret = write(fd, str, len);
+ ssize_t ret = safe_write(fd, str, len);
if (ret <= 0) {
return -1;
}
diff --git a/spawn.c b/spawn.c
index 66f5f5e..5878122 100644
--- a/spawn.c
+++ b/spawn.c
@@ -189,12 +189,9 @@ static void bfs_spawn_exec(const char *exe, const struct bfs_spawn *ctx, char **
fail:
error = errno;
- while (write(pipefd[1], &error, sizeof(error)) < 0) {
- if (errno != EINTR) {
- // Parent will still see that we exited unsuccessfully, but won't know why
- break;
- }
- }
+ // In case of write error parent will still see that we exited
+ // unsuccessfully, but won't know why.
+ safe_write(pipefd[1], &error, sizeof(error));
close(pipefd[1]);
_Exit(127);
@@ -224,7 +221,7 @@ pid_t bfs_spawn(const char *exe, const struct bfs_spawn *ctx, char **argv, char
// Parent
close(pipefd[1]);
- ssize_t nbytes = read(pipefd[0], &error, sizeof(error));
+ ssize_t nbytes = safe_read(pipefd[0], &error, sizeof(error));
close(pipefd[0]);
if (nbytes == sizeof(error)) {
int wstatus;
diff --git a/util.c b/util.c
index 42e3d98..611d4b5 100644
--- a/util.c
+++ b/util.c
@@ -368,3 +368,23 @@ int bfs_minor(dev_t dev) {
return dev & 0xFF;
#endif
}
+
+ssize_t safe_read(int fd, void *buf, size_t nbytes) {
+ for (;;) {
+ ssize_t ret = read(fd, buf, nbytes);
+ if (ret < 0 && errno == EINTR) {
+ continue;
+ }
+ return ret;
+ }
+}
+
+ssize_t safe_write(int fd, const void *buf, size_t nbytes) {
+ for (;;) {
+ ssize_t ret = write(fd, buf, nbytes);
+ if (ret < 0 && errno == EINTR) {
+ continue;
+ }
+ return ret;
+ }
+}
diff --git a/util.h b/util.h
index ca90494..ef67566 100644
--- a/util.h
+++ b/util.h
@@ -225,4 +225,14 @@ int bfs_major(dev_t dev);
*/
int bfs_minor(dev_t dev);
+/**
+ * A safe version of read() that handles interrupted system calls.
+ */
+ssize_t safe_read(int fd, void *buf, size_t nbytes);
+
+/**
+ * A safe version of write() that handles interrupted system calls.
+ */
+ssize_t safe_write(int fd, const void *buf, size_t nbytes);
+
#endif // BFS_UTIL_H