From 0e73390efffbeb76ea3eb739767b1c04e1641051 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Sat, 10 Jul 2021 17:24:18 +0200
Subject: name.c: Implement -x flag

---
 name.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 78 insertions(+), 10 deletions(-)

diff --git a/name.c b/name.c
index a53d7e0..26f6c8c 100644
--- a/name.c
+++ b/name.c
@@ -4,57 +4,125 @@
 #include <unistd.h>
 #include <string.h>
 #include <sys/select.h>
+#include <sys/wait.h>
 
-#define MAXFILES 100	/* Maximum number of files. */
-#define MAXFILE 255	/* Maximum file name length. */
-#define MAXLINE MAXFILE+1
+#define MAXFILES 100		/* Maximum number of files. */
+#define MAXFILE 255		/* Maximum file name length. */
+#define MAXLINE MAXFILE+1	/* Extra room for newline. */
 
+extern char *optarg;
+extern int optind;
+
+void escape(char *, char **);
 void waitstdin(void);
 
 int
 main(int argc, char *argv[])
 {
-	char file[30];
-	char from[MAXLINE], *froms[MAXFILES], to[MAXLINE], *tos[MAXFILES];
-	FILE *fp;
-	int i, j;
+	char	file[30], *name, from[MAXLINE], *froms[MAXFILES],
+		*tmp, to[MAXLINE], *tos[MAXFILES];
+	FILE	*fp;
+	int	c, i, j, s, xflag;
 
 	/* Allocate memory. */
 	for (i = 0; i < MAXFILES; i++)
 		if (!(froms[i]=malloc(MAXFILE)) || !(tos[i]=malloc(MAXFILE)))
 			err(1, "malloc");
+	if (!(tmp = malloc(MAXLINE*4)))
+		err(1, "malloc");
 
 	sprintf(file, "/var/tmp/re.%d", getppid());
 
+	/*
+	 * The existence of the temporary file is only checked when there
+	 * is input to be read on standard in, as re(1) doesn't create
+	 * the file until it starts writing on standard out.
+	 */
 	if (waitstdin(), access(file, F_OK)) {
 		fprintf(stderr, "%s: %s does not exist\n", argv[0], file);
 		return 1;
 	}
 
+	/* Read command-line options. */
+	name = argv[0];
+	xflag = 0;
+	while ((c = getopt(argc, argv, "x")) != -1)
+		switch (c) {
+		case 'x':
+			xflag = 1;
+			break;
+		default:
+			goto usage;
+		}
+	argc -= optind;
+	argv += optind;
+	if (argc > 0) {
+usage:		fprintf(stderr, "usage: %s [-x]\n", name);
+		return 1;
+	}
+
 	if (!(fp = fopen(file, "r")))
 		err(1, "fopen");
 
+	/* Read original file names. */
 	for (i = 0; fgets(from, MAXLINE, fp); i++) {
 		from[strcspn(from, "\n")] = 0;
 		strcpy(froms[i], from);
-		printf("from %s\n", from);
 	}
 
+	/* Read new file names. */
 	for (j = 0; fgets(to, MAXLINE, stdin); j++) {
 		to[strcspn(to, "\n")] = 0;
 		strcpy(tos[j], to);
-		printf("to %s\n", to);
 	}
 
 	if (i != j) {
 		fprintf(stderr, "%s: too %s lines\n",
-			argv[0], j > i ? "many" : "few");
+			name, j > i ? "many" : "few");
 		return 1;
 	}
 
+	/*
+	 * The corresponding mv invocations are printed on standard out.
+	 * If the -x flag is given, they are executed too.
+	 */
+	for (i = 0; i < j; i++) {
+		escape(froms[i], &tmp);	printf("mv '%s'", tmp);
+		escape(tos[i], &tmp);	printf(" '%s'\n", tmp);
+		if (xflag) {
+			if (!fork()) {
+				execl("/bin/mv", "mv", froms[i], tos[i], NULL);
+				err(1, "execl");
+			}
+			if (wait(&s), s) {
+				fprintf(stderr, "/bin/mv exited with %d\n",
+					WEXITSTATUS(s));
+				return 1;
+			}
+		}
+	}
+
+	unlink(file);
+
 	fclose(fp);
 }
 
+void
+escape(char *str, char **res)
+{
+	int i, j, offset;
+
+	for (i = j = 0; str[i]; i++) {
+		if (str[i] == '\'') {
+			strcat(*res, "'\\''");
+			j += 4;
+		} else
+			(*res)[j++] = str[i];
+	}
+
+	(*res)[j] = 0;
+}
+
 void
 waitstdin()
 {
-- 
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