xread/xwrite: do not worry about EINTR at calling sites.

We had errno==EINTR check after read(2)/write(2) sprinkled all
over the places, always doing continue.  Consolidate them into
xread()/xwrite() wrapper routines.

Credits for suggestion goes to HPA -- bugs are mine.

Signed-off-by: Junio C Hamano <junkio@cox.net>

apply.c

@@ -84,14 +84,11 @@ static void *read_patch_file(int fd, unsigned long *sizep)
 			buffer = xrealloc(buffer, alloc);
 			nr = alloc - size;
 		}
-		nr = read(fd, buffer + size, nr);
+		nr = xread(fd, buffer + size, nr);
 		if (!nr)
 			break;
-		if (nr < 0) {
-			if (errno == EAGAIN)
-				continue;
+		if (nr < 0)
 			die("git-apply: read returned %s", strerror(errno));
-		}
 		size += nr;
 	}
 	*sizep = size;
@@ -1006,13 +1003,8 @@ static int read_old_data(struct stat *st, const char *path, void *buf, unsigned
 			return error("unable to open %s", path);
 		got = 0;
 		for (;;) {
-			int ret = read(fd, buf + got, size - got);
-			if (ret < 0) {
-				if (errno == EAGAIN)
-					continue;
-				break;
-			}
-			if (!ret)
+			int ret = xread(fd, buf + got, size - got);
+			if (ret <= 0)
 				break;
 			got += ret;
 		}
@@ -1600,12 +1592,9 @@ static int try_create_file(const char *path, unsigned int mode, const char *buf,
 	if (fd < 0)
 		return -1;
 	while (size) {
-		int written = write(fd, buf, size);
-		if (written < 0) {
-			if (errno == EINTR || errno == EAGAIN)
-				continue;
+		int written = xwrite(fd, buf, size);
+		if (written < 0)
 			die("writing file %s: %s", path, strerror(errno));
-		}
 		if (!written)
 			die("out of space writing file %s", path);
 		buf += written;

cat-file.c

@@ -55,10 +55,8 @@ int main(int argc, char **argv)
 		die("git-cat-file %s: bad file", argv[2]);
 
 	while (size > 0) {
-		long ret = write(1, buf, size);
+		long ret = xwrite(1, buf, size);
 		if (ret < 0) {
-			if (errno == EAGAIN)
-				continue;
 			/* Ignore epipe */
 			if (errno == EPIPE)
 				break;

copy.c

@@ -6,30 +6,25 @@ int copy_fd(int ifd, int ofd)
 		int len;
 		char buffer[8192];
 		char *buf = buffer;
-		len = read(ifd, buffer, sizeof(buffer));
+		len = xread(ifd, buffer, sizeof(buffer));
 		if (!len)
 			break;
 		if (len < 0) {
 			int read_error;
-			if (errno == EAGAIN)
-				continue;
 			read_error = errno;
 			close(ifd);
 			return error("copy-fd: read returned %s",
 				     strerror(read_error));
 		}
-		while (1) {
-			int written = write(ofd, buf, len);
+		while (len) {
+			int written = xwrite(ofd, buf, len);
 			if (written > 0) {
 				buf += written;
 				len -= written;
-				if (!len)
-					break;
 			}
-			if (!written)
+			else if (!written)
 				return error("copy-fd: write returned 0");
-			if (errno == EAGAIN || errno == EINTR)
-				continue;
+			else
 				return error("copy-fd: write returned %s",
 					     strerror(errno));
 		}

csum-file.c

@@ -15,7 +15,7 @@ static int sha1flush(struct sha1file *f, unsigned int count)
 	void *buf = f->buffer;
 
 	for (;;) {
-		int ret = write(f->fd, buf, count);
+		int ret = xwrite(f->fd, buf, count);
 		if (ret > 0) {
 			buf += ret;
 			count -= ret;
@@ -25,8 +25,6 @@ static int sha1flush(struct sha1file *f, unsigned int count)
 		}
 		if (!ret)
 			die("sha1 file '%s' write error. Out of diskspace", f->name);
-		if (errno == EAGAIN || errno == EINTR)
-			continue;
 		die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
 	}
 }

git-compat-util.h

@@ -84,6 +84,28 @@ static inline void *xcalloc(size_t nmemb, size_t size)
 	return ret;
 }
 
+static inline ssize_t xread(int fd, void *buf, size_t len)
+{
+	ssize_t nr;
+	while (1) {
+		nr = read(fd, buf, len);
+		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
+			continue;
+		return nr;
+	}
+}
+
+static inline ssize_t xwrite(int fd, const void *buf, size_t len)
+{
+	ssize_t nr;
+	while (1) {
+		nr = write(fd, buf, len);
+		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
+			continue;
+		return nr;
+	}
+}
+
 /* Sane ctype - no locale, and works with signed chars */
 #undef isspace
 #undef isdigit

mktag.c

@@ -116,14 +116,9 @@ int main(int argc, char **argv)
 	// Read the signature
 	size = 0;
 	for (;;) {
-		int ret = read(0, buffer + size, MAXSIZE - size);
-		if (!ret)
+		int ret = xread(0, buffer + size, MAXSIZE - size);
+		if (ret <= 0)
 			break;
-		if (ret < 0) {
-			if (errno == EAGAIN)
-				continue;
-			break;
-		}
 		size += ret;
 	}
 

pkt-line.c

@@ -19,7 +19,7 @@
 static void safe_write(int fd, const void *buf, unsigned n)
 {
 	while (n) {
-		int ret = write(fd, buf, n);
+		int ret = xwrite(fd, buf, n);
 		if (ret > 0) {
 			buf += ret;
 			n -= ret;
@@ -27,8 +27,6 @@ static void safe_write(int fd, const void *buf, unsigned n)
 		}
 		if (!ret)
 			die("write error (disk full?)");
-		if (errno == EAGAIN || errno == EINTR)
-			continue;
 		die("write error (%s)", strerror(errno));
 	}
 }
@@ -68,12 +66,9 @@ static void safe_read(int fd, void *buffer, unsigned size)
 	int n = 0;
 
 	while (n < size) {
-		int ret = read(fd, buffer + n, size - n);
-		if (ret < 0) {
-			if (errno == EINTR || errno == EAGAIN)
-				continue;
+		int ret = xread(fd, buffer + n, size - n);
+		if (ret < 0)
 			die("read error (%s)", strerror(errno));
-		}
 		if (!ret)
 			die("unexpected EOF");
 		n += ret;

tar-tree.c

@@ -34,10 +34,8 @@ struct path_prefix {
 static void reliable_write(void *buf, unsigned long size)
 {
 	while (size > 0) {
-		long ret = write(1, buf, size);
+		long ret = xwrite(1, buf, size);
 		if (ret < 0) {
-			if (errno == EAGAIN)
-				continue;
 			if (errno == EPIPE)
 				exit(0);
 			die("git-tar-tree: %s", strerror(errno));

unpack-objects.c

@@ -31,12 +31,10 @@ static void * fill(int min)
 		offset = 0;
 	}
 	do {
-		int ret = read(0, buffer + len, sizeof(buffer) - len);
+		int ret = xread(0, buffer + len, sizeof(buffer) - len);
 		if (ret <= 0) {
 			if (!ret)
 				die("early EOF");
-			if (errno == EAGAIN || errno == EINTR)
-				continue;
 			die("read error on input: %s", strerror(errno));
 		}
 		len += ret;
@@ -299,14 +297,9 @@ int main(int argc, char **argv)
 
 	/* Write the last part of the buffer to stdout */
 	while (len) {
-		int ret = write(1, buffer + offset, len);
-		if (!ret)
+		int ret = xwrite(1, buffer + offset, len);
+		if (ret <= 0)
 			break;
-		if (ret < 0) {
-			if (errno == EAGAIN || errno == EINTR)
-				continue;
-			break;
-		}
 		len -= ret;
 		offset += ret;
 	}