pipeln

commit 45f674aa80b6cec9c95e12ea086e06811ccbdeb2
parent 25aef9010259cf14d0b9a138cbadc13740feaff5
Author: Louis Burda <quent.burda@gmail.com>
Date:   Sun, 14 Jul 2024 07:21:14 +0200

Prevent re-closing input pipe file descriptor

Diffstat:
M
Makefile
 | 
8
+++++++-
M
pipeln.c
 | 
55
+++++++++++++++++++++++++++----------------------------

2 files changed, 34 insertions(+), 29 deletions(-)
diff --git a/Makefile b/Makefile
@@ -1,7 +1,13 @@
 PREFIX ?= /usr/local
 BINDIR ?= /bin
 
-CFLAGS = -std=c99 -Wunused-variable -Wunused-function -Wconversion -O2
+CFLAGS = -std=c99 -Wunused-variable -Wunused-function -Wconversion
+
+ifeq ($(DEBUG), 1)
+CFLAGS += -Og -g
+else
+CFLAGS +=  -O2
+endif
 
 all: pipeln
 
diff --git a/pipeln.c b/pipeln.c
@@ -1,12 +1,8 @@
-#include <asm-generic/errno-base.h>
-#include <linux/limits.h>
 #include <sys/wait.h>
 #include <unistd.h>
 #include <dirent.h>
 #include <wait.h>
-
 #include <errno.h>
-#include <limits.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <string.h>
@@ -21,6 +17,7 @@ die(const char *fmt, ...)
 {
 	va_list ap;
 
+	setvbuf(stderr, NULL, _IOLBF, 0);
 	fputs("pipeln: ", stderr);
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
@@ -35,6 +32,13 @@ die(const char *fmt, ...)
 	exit(1);
 }
 
+static void
+usage(int rc, FILE *file)
+{
+	fprintf(file, "Usage: pipeln [-h] [-R] [--] [CMD |].. CMD\n");
+	exit(rc);
+}
+
 static pid_t
 run(int *in, int *out, const char **argv)
 {
@@ -48,15 +52,15 @@ run(int *in, int *out, const char **argv)
 	if (!child) {
 		if (in) {
 			if (dup2(in[0], 0) < 0)
-				die("dup2:");
-			close(in[0]);
-			close(in[1]);
+				die("dup2 %i:", errno);
+			if (close(in[0]) < 0)
+				die("close:"); 
 		}
 		if (out) {
 			if (dup2(out[1], 1) < 0)
 				die("dup2:");
-			close(out[0]);
-			close(out[1]);
+			if (close(out[0]) < 0 || close(out[1]) < 0)
+				die("close:"); 
 		}
 		if (resolve_bin) {
 			execvp(argv[0], (char *const *) argv);
@@ -99,48 +103,43 @@ int
 main(int argc, const char **argv)
 {
 	const char **arg, **cmdargs;
-	const char *invalid;
 	int pipe1[2], pipe2[2];
 	int *in, *out;
 	pid_t pid;
 
-	/* first cmd from stdin */
-	in = NULL;
-	out = pipe2;
-
 	if (argc < 1) return 1;
 
-	invalid = NULL;
-	cmdargs = NULL;
 	for (arg = argv + 1; *arg; arg++) {
 		if (!strcmp(*arg, "--")) {
-			cmdargs = arg;
+			arg++;
 			break;
-		} else if (!strcmp(*arg, "-x")) {
+		} else if (!strcmp(*arg, "-h")) {
+			usage(1, stderr);
+		} else if (!strcmp(*arg, "-R")) {
 			resolve_bin = false;
 		} else {
-			invalid = *arg;
+			break;
 		}
 	}
-	if (!cmdargs) die("missing -- separator");
-	if (invalid) die("invalid argument '%s'", invalid);
 
-	cmdargs += 1;
-	for (arg = argv + 1; ; arg++) {
+	// First command from stdin.
+	in = NULL;
+	out = pipe1;
+
+	cmdargs = arg;
+	for (; ; arg++) {
 		if (!*arg || !strcmp(*arg, "|")) {
-			/* last cmd goes to stdout */
+			// Last command to stdout.
 			if (!*arg) out = NULL;
-			else if (pipe(out)) die("pipe:");
+			else if (pipe(out) < 0) die("pipe:");
 
-			/* run piped cmd */
 			*arg = NULL;
 			pid = run(in, out, cmdargs);
 			if (!out) waitall(pid);
 			cmdargs = arg + 1;
 
-			/* out => in */
 			in = out;
-			out = out == pipe1 ? pipe2 : pipe1;
+			out = (out == pipe1) ? pipe2 : pipe1;
 		} else if (!strcmp(*arg, "\\|")) {
 			*arg = "|";
 		}