Rewrite nc to be simpler, smaller, and to check syscalls for errors.

busybox.h

@@ -147,6 +147,7 @@ int makeString(int argc, const char **argv, char *buf, int bufLen);
 char *getChunk(int size);
 char *chunkstrdup(const char *str);
 void freeChunks(void);
+ssize_t safe_read(int fd, void *buf, size_t count);
 int full_write(int fd, const char *buf, int len);
 int full_read(int fd, char *buf, int len);
 int recursive_action(const char *fileName, int recurse, int followLinks, int depthFirst,

include/busybox.h

@@ -147,6 +147,7 @@ int makeString(int argc, const char **argv, char *buf, int bufLen);
 char *getChunk(int size);
 char *chunkstrdup(const char *str);
 void freeChunks(void);
+ssize_t safe_read(int fd, void *buf, size_t count);
 int full_write(int fd, const char *buf, int len);
 int full_read(int fd, char *buf, int len);
 int recursive_action(const char *fileName, int recurse, int followLinks, int depthFirst,

nc.c

@@ -38,14 +38,10 @@
 #include <sys/time.h>
 #include <sys/ioctl.h>
 
-#define BUFSIZE 100
-
 int nc_main(int argc, char **argv)
 {
 	int sfd;
-	int result;
+	char buf[BUFSIZ];
-	int len;
-	char ch[BUFSIZE];
 
 	struct sockaddr_in address;
 	struct hostent *hostinfo;
@@ -54,34 +50,26 @@ int nc_main(int argc, char **argv)
 
 	argc--;
 	argv++;
-	if (argc < 2 || **(argv + 1) == '-') {
+	if (argc < 2 || **argv == '-') {
 		usage(nc_usage);
 	}
 
-	sfd = socket(AF_INET, SOCK_STREAM, 0);
+	if ((sfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+		perror_msg_and_die("socket");
 
-	hostinfo = (struct hostent *) gethostbyname(*argv);
+	if ((hostinfo = gethostbyname(*argv)) == NULL)
-
-	if (!hostinfo) {
 		error_msg_and_die("cannot resolve %s\n", *argv);
-	}
 
 	address.sin_family = AF_INET;
 	address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
 	address.sin_port = htons(atoi(*(++argv)));
 
-	len = sizeof(address);
+	if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
-
+		perror_msg_and_die("connect");
-	result = connect(sfd, (struct sockaddr *) &address, len);
-
-	if (result < 0) {
-		perror("nc: connect");
-		exit(2);
-	}
 
 	FD_ZERO(&readfds);
 	FD_SET(sfd, &readfds);
-	FD_SET(fileno(stdin), &readfds);
+	FD_SET(STDIN_FILENO, &readfds);
 
 	while (1) {
 		int fd;
@@ -90,41 +78,26 @@ int nc_main(int argc, char **argv)
 
 		testfds = readfds;
 
-		result =
+		if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
-			select(FD_SETSIZE, &testfds, (fd_set *) NULL, (fd_set *) NULL,
+			perror_msg_and_die("select");
-				   (struct timeval *) 0);
-
-		if (result < 1) {
-			perror("nc: select");
-			exit(3);
-		}
 
 		for (fd = 0; fd < FD_SETSIZE; fd++) {
 			if (FD_ISSET(fd, &testfds)) {
-				int trn = 0;
+				if ((nread = safe_read(fd, buf, sizeof(buf))) < 0)
-				int rn;
+					perror_msg_and_die("read");
-
-				ioctl(fd, FIONREAD, &nread);
 
 				if (fd == sfd) {
 					if (nread == 0)
 						exit(0);
-					ofd = fileno(stdout);
+					ofd = STDOUT_FILENO;
 				} else {
 					if (nread == 0)
 						shutdown(sfd, 1);
 					ofd = sfd;
 				}
 
-
+				if (full_write(ofd, buf, nread) < 0)
-
+					perror_msg_and_die("write");
-				do {
-					rn = (BUFSIZE < nread - trn) ? BUFSIZE : nread - trn;
-					trn += rn;
-					read(fd, ch, rn);
-					write(ofd, ch, rn);
-				}
-				while (trn < nread);
 			}
 		}
 	}

networking/nc.c

@@ -38,14 +38,10 @@
 #include <sys/time.h>
 #include <sys/ioctl.h>
 
-#define BUFSIZE 100
-
 int nc_main(int argc, char **argv)
 {
 	int sfd;
-	int result;
+	char buf[BUFSIZ];
-	int len;
-	char ch[BUFSIZE];
 
 	struct sockaddr_in address;
 	struct hostent *hostinfo;
@@ -54,34 +50,26 @@ int nc_main(int argc, char **argv)
 
 	argc--;
 	argv++;
-	if (argc < 2 || **(argv + 1) == '-') {
+	if (argc < 2 || **argv == '-') {
 		usage(nc_usage);
 	}
 
-	sfd = socket(AF_INET, SOCK_STREAM, 0);
+	if ((sfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+		perror_msg_and_die("socket");
 
-	hostinfo = (struct hostent *) gethostbyname(*argv);
+	if ((hostinfo = gethostbyname(*argv)) == NULL)
-
-	if (!hostinfo) {
 		error_msg_and_die("cannot resolve %s\n", *argv);
-	}
 
 	address.sin_family = AF_INET;
 	address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
 	address.sin_port = htons(atoi(*(++argv)));
 
-	len = sizeof(address);
+	if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
-
+		perror_msg_and_die("connect");
-	result = connect(sfd, (struct sockaddr *) &address, len);
-
-	if (result < 0) {
-		perror("nc: connect");
-		exit(2);
-	}
 
 	FD_ZERO(&readfds);
 	FD_SET(sfd, &readfds);
-	FD_SET(fileno(stdin), &readfds);
+	FD_SET(STDIN_FILENO, &readfds);
 
 	while (1) {
 		int fd;
@@ -90,41 +78,26 @@ int nc_main(int argc, char **argv)
 
 		testfds = readfds;
 
-		result =
+		if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
-			select(FD_SETSIZE, &testfds, (fd_set *) NULL, (fd_set *) NULL,
+			perror_msg_and_die("select");
-				   (struct timeval *) 0);
-
-		if (result < 1) {
-			perror("nc: select");
-			exit(3);
-		}
 
 		for (fd = 0; fd < FD_SETSIZE; fd++) {
 			if (FD_ISSET(fd, &testfds)) {
-				int trn = 0;
+				if ((nread = safe_read(fd, buf, sizeof(buf))) < 0)
-				int rn;
+					perror_msg_and_die("read");
-
-				ioctl(fd, FIONREAD, &nread);
 
 				if (fd == sfd) {
 					if (nread == 0)
 						exit(0);
-					ofd = fileno(stdout);
+					ofd = STDOUT_FILENO;
 				} else {
 					if (nread == 0)
 						shutdown(sfd, 1);
 					ofd = sfd;
 				}
 
-
+				if (full_write(ofd, buf, nread) < 0)
-
+					perror_msg_and_die("write");
-				do {
-					rn = (BUFSIZE < nread - trn) ? BUFSIZE : nread - trn;
-					trn += rn;
-					read(fd, ch, rn);
-					write(ofd, ch, rn);
-				}
-				while (trn < nread);
 			}
 		}
 	}

utility.c

@@ -536,7 +536,7 @@ const char *time_string(time_t timeVal)
 }
 #endif /* BB_TAR || BB_AR */
 
-#if defined BB_TAR || defined BB_CP_MV || defined BB_AR || defined BB_DD
+#if defined BB_AR || defined BB_CP_MV || defined BB_DD || defined BB_NC || defined BB_TAR
 /*
  * Write all of the supplied buffer out to a file.
  * This does multiple writes as necessary.
@@ -1791,6 +1791,19 @@ int applet_name_compare(const void *x, const void *y)
 	return strcmp(applet1->name, applet2->name);
 }
 
+#if defined BB_NC
+ssize_t safe_read(int fd, void *buf, size_t count)
+{
+	ssize_t n;
+
+	do {
+		n = read(fd, buf, count);
+	} while (n < 0 && errno == EINTR);
+
+	return n;
+}
+#endif
+
 /* END CODE */
 /*
 Local Variables: