Add utility functions to read()/write() safely

Automatically handle short reads due to singals interrupting the process.

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-by: Günther Deschner <gdeschner@redhat.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/proxy/src/gp_common.h b/proxy/src/gp_common.h
index f2b8c3e..3a1b7be 100644
--- a/proxy/src/gp_common.h
+++ b/proxy/src/gp_common.h
@@ -69,6 +69,8 @@ bool gp_same(const char *a, const char *b);
 bool gp_boolean_is_true(const char *s);
 char *gp_getenv(const char *name);
 
+ssize_t gp_safe_read(int fd, void *buf, size_t count);
+ssize_t gp_safe_write(int fd, const void *buf, size_t count);
 /* NOTE: read the note in gp_util.c before using gp_strerror() */
 char *gp_strerror(int errnum);
 
diff --git a/proxy/src/gp_util.c b/proxy/src/gp_util.c
index 4fbac4e..34f3024 100644
--- a/proxy/src/gp_util.c
+++ b/proxy/src/gp_util.c
@@ -29,6 +29,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <errno.h>
+#include <unistd.h>
 
 bool gp_same(const char *a, const char *b)
 {
@@ -125,3 +126,41 @@ char *gp_strerror(int errnum)
     errno = saved_errno;
     return buf;
 }
+
+ssize_t gp_safe_read(int fd, void *buf, size_t count)
+{
+    char *b = (char *)buf;
+    ssize_t len = 0;
+    ssize_t ret;
+
+    do {
+        ret = read(fd, &b[len], count - len);
+        if (ret == -1) {
+            if (errno == EINTR) continue;
+            return ret;
+        }
+        if (ret == 0) break; /* EOF */
+        len += ret;
+    } while (count > len);
+
+    return len;
+}
+
+ssize_t gp_safe_write(int fd, const void *buf, size_t count)
+{
+    const char *b = (const char *)buf;
+    ssize_t len = 0;
+    ssize_t ret;
+
+    do {
+        ret = write(fd, &b[len], count - len);
+        if (ret == -1) {
+            if (errno == EINTR) continue;
+            return ret;
+        }
+        if (ret == 0) break; /* EOF */
+        len += ret;
+    } while (count > len);
+
+    return len;
+}