Communicate whether file transfers were completed

Signed-off-by: Mattias Andrée <maandree@kth.se>

5 files changed, 117 insertions, 86 deletions

diff --git a/Makefile b/Makefile
index eff2603..74bce68 100644
--- a/Makefile
+++ b/Makefile
@@ -5,19 +5,23 @@ include $(CONFIGFILE)
 
 OBJ =\
 	editasroot.o\
+	common.o\
 	copier.o
 
+HDR =\
+	common.h
+
 all: editasroot copier
-$(OBJ): $(@:.o=.c)
+$(OBJ): $(HDR)
 
 .c.o:
 	$(CC) -c -o $@ $< $(CFLAGS) $(CPPFLAGS)
 
-editasroot: editasroot.o
-	$(CC) -o $@ $@.o $(LDFLAGS)
+editasroot: editasroot.o common.o
+	$(CC) -o $@ $@.o common.o $(LDFLAGS)
 
-copier: copier.o
-	$(CC) -o $@ $@.o $(LDFLAGS)
+copier: copier.o common.o
+	$(CC) -o $@ $@.o common.o $(LDFLAGS)
 
 install: editasroot copier
 	mkdir -p -- "$(DESTDIR)$(PREFIX)/bin"
diff --git a/common.c b/common.c
new file mode 100644
index 0000000..5379f89
--- /dev/null
+++ b/common.c
@@ -0,0 +1,53 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+void
+copy_file(int destfd, const char *destfname, int srcfd, const char *srcfname, int *okp)
+{
+	char buf[BUFSIZ];
+	ssize_t r, w, p, ok_off;
+	size_t read_off;
+
+	if (okp) {
+		*okp = 0;
+		ok_off = 1;
+		read_off = 0;
+	} else {
+		ok_off = 0;
+		read_off = 1;
+		buf[0] = 0;
+	}
+
+	for (;;) {
+		r = read(srcfd, &buf[read_off], sizeof(buf) - read_off);
+		if (r <= 0) {
+			if (!r)
+				break;
+			fprintf(stderr, "%s: read %s: %s", argv0, srcfname, strerror(errno));
+			exit(1);
+		}
+
+		if (r == ok_off) { /* Only possible if okp != NULL */
+			*okp = 1;
+			break;
+		}
+
+		r += (ssize_t)read_off;
+		for (p = ok_off; p < r; p += w) {
+			w = write(destfd, buf, (size_t)(r - p));
+			if (r <= 0) {
+				fprintf(stderr, "%s: write %s: %s", argv0, destfname, strerror(errno));
+				exit(1);
+			}
+		}
+	}
+
+	if (!okp) {
+		w = write(destfd, buf, 1);
+		if (r <= 0) {
+			fprintf(stderr, "%s: write %s: %s", argv0, destfname, strerror(errno));
+			exit(1);
+		}
+	}
+}
diff --git a/common.h b/common.h
new file mode 100644
index 0000000..ac73c43
--- /dev/null
+++ b/common.h
@@ -0,0 +1,34 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+
+/* We need at least 2 bytes we are sending 1 addition byte in each chunk */
+#if BUFSIZ < 2
+# undef BUFSIZ
+# define BUFSIZ 2
+#endif
+
+/* We impose a limit because PF_UNIX/SOCK_SEQPACKET can block if sending
+ * too much (I don't know the exact limit and it can change), without
+ * first setting up a socket options, which is overkill for this application,
+ * and there is also a hard limit just above 210000B for each EMSGSIZE will
+ * be thrown. */
+#if BUFSIZ > (8 << 10)
+# undef BUFSIZ
+# define BUFSIZ (8 << 10)
+#endif
+
+
+extern const char *argv0;
+
+void copy_file(int destfd, const char *destfname, int srcfd, const char *srcfname, int *okp);
diff --git a/copier.c b/copier.c
index 231e515..3e7a6c6 100644
--- a/copier.c
+++ b/copier.c
@@ -1,46 +1,14 @@
 /* See LICENSE file for copyright and license details. */
-#include <sys/socket.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
+#include "common.h"
 
 
-static const char *argv0 = "editasroot/copier";
-
-
-static void
-copy_file(int destfd, const char *destfname, int srcfd, const char *srcfname)
-{
-	char buf[BUFSIZ];
-	ssize_t r, w, p;
-
-	for (;;) {
-		r = read(srcfd, buf, sizeof(buf));
-		if (r <= 0) {
-			if (!r)
-				break;
-			fprintf(stderr, "%s: read %s: %s", argv0, srcfname, strerror(errno));
-			exit(1);
-		}
-
-		for (p = 0; p < r; p += w) {
-			w = write(destfd, buf, (size_t)(r - p));
-			if (r <= 0) {
-				fprintf(stderr, "%s: write %s: %s", argv0, destfname, strerror(errno));
-				exit(1);
-			}
-		}
-	}
-}
+const char *argv0 = "editasroot/copier";
 
 
 int
 main(int argc, char *argv[])
 {
-	int filefd, parentfd;
+	int filefd, parentfd, ok;
 	const char *path;
 	ssize_t r;
 	char b;
@@ -59,7 +27,7 @@ main(int argc, char *argv[])
 		fprintf(stderr, "%s: open %s O_RDWR: %s\n", argv0, path, strerror(errno));
 		exit(1);
 	}
-	copy_file(parentfd, "<socket to parent>", filefd, path);
+	copy_file(parentfd, "<socket to parent>", filefd, path, NULL);
 	if (close(filefd)) {
 		fprintf(stderr, "%s: read %s: %s\n", argv0, path, strerror(errno));
 		exit(1);
@@ -81,7 +49,7 @@ main(int argc, char *argv[])
 		fprintf(stderr, "%s: open %s O_WRONLY|O_TRUNC: %s\n", argv0, path, strerror(errno));
 		exit(1);
 	}
-	copy_file(filefd, path, parentfd, "<socket to parent>");
+	copy_file(filefd, path, parentfd, "<socket to parent>", &ok);
 	if (close(filefd)) {
 		fprintf(stderr, "%s: write %s: %s\n", argv0, path, strerror(errno));
 		exit(1);
@@ -90,6 +58,10 @@ main(int argc, char *argv[])
 		fprintf(stderr, "%s: read <socket to parent>: %s\n", argv0, strerror(errno));
 		exit(1);
 	}
+	if (!ok) {
+		fprintf(stderr, "%s: parent exited before sending file termination message, file may be truncated\n", argv0);
+		exit(1);
+	}
 
 	return 0;
 }
diff --git a/editasroot.c b/editasroot.c
index c6ce396..09479f8 100644
--- a/editasroot.c
+++ b/editasroot.c
@@ -1,21 +1,11 @@
 /* See LICENSE file for copyright and license details. */
-#include <sys/prctl.h>
-#include <sys/socket.h>
-#include <sys/wait.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <paths.h>
-#include <signal.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <termios.h>
-#include <unistd.h>
+#include "common.h"
 
 #define TEMPFILEPATTERN "tmpXXXXXX"
 
 
-static const char *argv0 = "editasroot";
+const char *argv0 = "editasroot";
+
 static const char *unlink_this = NULL;
 static int ttyfd = -1;
 static int tcattrs_fetched = 0;
@@ -101,32 +91,6 @@ get_tmpfile_pattern(void)
 }
 
 
-static void
-copy_file(int destfd, const char *destfname, int srcfd, const char *srcfname)
-{
-	char buf[BUFSIZ];
-	ssize_t r, w, p;
-
-	for (;;) {
-		r = read(srcfd, buf, sizeof(buf));
-		if (r <= 0) {
-			if (!r)
-				break;
-			fprintf(stderr, "%s: read %s: %s", argv0, srcfname, strerror(errno));
-			exit(1);
-		}
-
-		for (p = 0; p < r; p += w) {
-			w = write(destfd, buf, (size_t)(r - p));
-			if (r <= 0) {
-				fprintf(stderr, "%s: write %s: %s", argv0, destfname, strerror(errno));
-				exit(1);
-			}
-		}
-	}
-}
-
-
 static pid_t
 run_child(const char *file, int fd, int close_this)
 {
@@ -191,7 +155,7 @@ main(int argc, char *argv[])
 {
 	const char *editor;
 	char *path;
-	int fd, fds[2], status, i;
+	int fd, fds[2], status, i, ok;
 	pid_t pid;
 
 	if (!argc)
@@ -226,8 +190,8 @@ main(int argc, char *argv[])
 	editor = get_editor();
 
 	/* Start copier, with a bidirectional channel to it for copying the file */
-	if (socketpair(PF_LOCAL, SOCK_STREAM, 0, fds)) {
-		fprintf(stderr, "%s: socketpair PF_LOCAL SOCK_STREAM 0: %s", argv0, strerror(errno));
+	if (socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, fds)) {
+		fprintf(stderr, "%s: socketpair PF_LOCAL SOCK_SEQPACKET 0: %s", argv0, strerror(errno));
 		exit(1);
 	}
 	pid = run_child(argv[0], fds[1], fds[0]);
@@ -246,7 +210,7 @@ main(int argc, char *argv[])
 		exit(1);
 	}
 	unlink_this = path;
-	copy_file(fd, path, fds[0], "<socket to child>");
+	copy_file(fd, path, fds[0], "<socket to child>", &ok);
 	if (close(fd)) {
 		fprintf(stderr, "%s: write %s: %s", argv0, path, strerror(errno));
 		exit(1);
@@ -255,6 +219,10 @@ main(int argc, char *argv[])
 		fprintf(stderr, "%s: shutdown <socket to child> SHUT_RD: %s\n", argv0, strerror(errno));
 		exit(1);
 	}
+	if (!ok) {
+		fprintf(stderr, "%s: child exited before sending file termination message\n", argv0);
+		exit(1);
+	}
 
 	/* Don't need to restore terminal attributes, if we got here, asroot as not interrupted */
 	close(ttyfd);
@@ -274,7 +242,7 @@ main(int argc, char *argv[])
 		fprintf(stderr, "%s: open %s O_RDONLY: %s", argv0, path, strerror(errno));
 		exit(1);
 	}
-	copy_file(fds[0], "<socket to child>", fd, path);
+	copy_file(fds[0], "<socket to child>", fd, path, NULL);
 	if (close(fd)) {
 		fprintf(stderr, "%s: read %s: %s", argv0, path, strerror(errno));
 		exit(1);