utils-std

commit: cff503f0a83af7a3ba4d6c26cdb5922720ddeabc
parent c368820dca8c75942de33e1ee7e80d284e63bacb
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Tue, 10 Sep 2024 09:37:58 +0200

cmd/cat: close stdin/stdout before returning successfully

Inspired by https://blog.sunfishcode.online/errors-from-close/

Diffstat:
M
cmd/cat.c
77
+++++++++++++++++++++++++++++++++++++++++++++++------------------------------

1 file changed, 47 insertions(+), 30 deletions(-)
diff --git a/cmd/cat.c b/cmd/cat.c
@@ -23,7 +23,7 @@ concat(int fd, const char *fdname)
 	while((c = read(fd, buf, sizeof(buf))) > 0)
 	{
 		assert(errno == 0);
-		if(write(1, buf, (size_t)c) < 0)
+		if(write(STDOUT_FILENO, buf, (size_t)c) < 0)
 		{
 			fprintf(stderr, "cat: Error writing: %s\n", strerror(errno));
 			errno = 0;
@@ -42,14 +42,14 @@ concat(int fd, const char *fdname)
 }
 
 #ifdef HAS_SPLICE
+#define FD_COPY_SPLICE_FLAGS SPLICE_F_MOVE | SPLICE_F_NONBLOCK | SPLICE_F_MORE
 static int
 fd_copy(int fd, const char *fdname)
 {
 	while(1)
 	{
 		assert(errno == 0);
-		ssize_t ret =
-		    splice(fd, NULL, 1, NULL, SIZE_MAX, SPLICE_F_MOVE | SPLICE_F_NONBLOCK | SPLICE_F_MORE);
+		ssize_t ret = splice(fd, NULL, STDOUT_FILENO, NULL, SIZE_MAX, FD_COPY_SPLICE_FLAGS);
 
 		if(ret == 0) break;
 
@@ -112,42 +112,59 @@ main(int argc, char *argv[])
 
 	if(argc < 1)
 	{
-		return fd_copy(0, "<stdin>");
+		if(fd_copy(STDIN_FILENO, "<stdin>") != 0)
+		{
+			return 1;
+		}
 	}
-
-	for(int argi = 0; argi < argc; argi++)
+	else
 	{
-		if(strncmp(argv[argi], "-", 2) == 0)
+		for(int argi = 0; argi < argc; argi++)
 		{
-			if(fd_copy(0, "<stdin>") != 0)
+			if(strncmp(argv[argi], "-", 2) == 0)
 			{
-				return 1;
+				if(fd_copy(STDIN_FILENO, "<stdin>") != 0)
+				{
+					return 1;
+				}
 			}
-		}
-		else
-		{
-			assert(errno == 0);
-			int fd = open(argv[argi], O_RDONLY);
-			if(fd < 0)
+			else
 			{
-				fprintf(stderr, "cat: Error opening ‘%s’: %s\n", argv[argi], strerror(errno));
-				errno = 0;
-				return 1;
+				assert(errno == 0);
+				int fd = open(argv[argi], O_RDONLY);
+				if(fd < 0)
+				{
+					fprintf(stderr, "cat: Error opening ‘%s’: %s\n", argv[argi], strerror(errno));
+					errno = 0;
+					return 1;
+				}
+
+				if(fd_copy(fd, argv[argi]) != 0)
+				{
+					return 1;
+				}
+
+				assert(errno == 0);
+				if(close(fd) < 0)
+				{
+					fprintf(stderr, "cat: Error closing ‘%s’: %s\n", argv[argi], strerror(errno));
+					errno = 0;
+					return 1;
+				}
 			}
+		}
+	}
 
-			if(fd_copy(fd, argv[argi]) != 0)
-			{
-				return 1;
-			}
+	if(close(STDIN_FILENO) != 0)
+	{
+		fprintf(stderr, "cat: Error closing <stdin>: %s\n", strerror(errno));
+		return 1;
+	}
 
-			assert(errno == 0);
-			if(close(fd) < 0)
-			{
-				fprintf(stderr, "cat: Error closing ‘%s’: %s\n", argv[argi], strerror(errno));
-				errno = 0;
-				return 1;
-			}
-		}
+	if(close(STDOUT_FILENO) != 0)
+	{
+		fprintf(stderr, "cat: Error closing <stdout>: %s\n", strerror(errno));
+		return 1;
 	}
 
 	return 0;