Audit cp() in libutil

1) Rename cp_HLPflag -> cp_follow for consistency.
2) Use function-pointers for stat to clear up the code.
3) BUGFIX: TERMINATE THE RESULT BUFFER OF READLINK !!!
   It's something I noticed earlier and it actually lead to some
   pretty insane behaviour on our side using glibc (musl somehow
   magically solves this).
   Basically, symlinks used to contain the data of the file they
   pointed to. I wondered for weeks where this came from and now
   this has finally been solved.
4) BUGFIX: Do not unconditionally unlink target-files. Even GNU
   coreutils do it wrong.
   The basic idea is this:
   If fflag == 0 --> don't touch target files if they exist.
   If fflag == 1 --> unlink all and don't error out when we try
                     to unlink a file which doesn't exist.
5) Use estrlcpy and estrlcat instead of snprintf for path building.
6) Make it clearer what happens in preserve.

cp.c

@@ -17,7 +17,7 @@ main(int argc, char *argv[])
 
 	ARGBEGIN {
 	case 'a':
-		cp_HLPflag = 'P';
+		cp_follow = 'P';
 		cp_aflag = cp_pflag = cp_rflag = 1;
 		break;
 	case 'f':
@@ -36,7 +36,7 @@ main(int argc, char *argv[])
 	case 'H':
 	case 'L':
 	case 'P':
-		cp_HLPflag = ARGC();
+		cp_follow = ARGC();
 		break;
 	default:
 		usage();

fs.h

@@ -25,7 +25,7 @@ extern int cp_fflag;
 extern int cp_pflag;
 extern int cp_rflag;
 extern int cp_vflag;
-extern int cp_HLPflag;
+extern int cp_follow;
 extern int cp_status;
 
 extern int rm_fflag;

libutil/cp.c

@@ -15,136 +15,162 @@
 #include "../text.h"
 #include "../util.h"
 
-int cp_aflag = 0;
-int cp_fflag = 0;
-int cp_pflag = 0;
-int cp_rflag = 0;
-int cp_vflag = 0;
+int cp_aflag  = 0;
+int cp_fflag  = 0;
+int cp_pflag  = 0;
+int cp_rflag  = 0;
+int cp_vflag  = 0;
 int cp_status = 0;
-int cp_HLPflag = 'L';
+int cp_follow = 'L';
 
 int
 cp(const char *s1, const char *s2, int depth)
 {
+	DIR *dp;
 	FILE *f1, *f2;
-	char ns1[PATH_MAX], ns2[PATH_MAX];
 	struct dirent *d;
 	struct stat st;
 	struct utimbuf ut;
-	char buf[PATH_MAX];
-	DIR *dp;
-	int r;
+	ssize_t r;
+	int (*statf)(const char *, struct stat *);
+	char target[PATH_MAX], ns1[PATH_MAX], ns2[PATH_MAX], *statf_name;
+
+	if (cp_follow == 'P' || (cp_follow == 'H' && depth)) {
+		statf_name = "lstat";
+		statf = lstat;
+	} else {
+		statf_name = "stat";
+		statf = stat;
+	}
+
+	if (statf(s1, &st) < 0) {
+		weprintf("%s %s:", statf_name, s1);
+		cp_status = 1;
+		return 0;
+	}
 
 	if (cp_vflag)
-		printf("'%s' -> '%s'\n", s1, s2);
-
-	r = (cp_HLPflag == 'P' || (cp_HLPflag == 'H' && depth > 0)) ?
-	    lstat(s1, &st) : stat(s1, &st);
-	if (r < 0) {
-		weprintf("%s %s:", (cp_HLPflag == 'P' ||
-		         (cp_HLPflag == 'H' && depth > 0)) ? "lstat" : "stat", s1);
-		cp_status = 1;
-		return 0;
-	}
+		printf("%s -> %s\n", s1, s2);
 
 	if (S_ISLNK(st.st_mode)) {
-		if (readlink(s1, buf, sizeof(buf) - 1) >= 0) {
-			if (cp_fflag)
-				unlink(s2);
-			if (symlink(buf, s2) != 0) {
-				weprintf("%s: can't create '%s'\n", argv0, s2);
+		if ((r = readlink(s1, target, sizeof(target) - 1)) >= 0) {
+			target[r] = '\0';
+			if (cp_fflag && unlink(s2) < 0 && errno != ENOENT) {
+				weprintf("unlink %s:", s2);
+				cp_status = 1;
+				return 0;
+			} else if (symlink(target, s2) < 0) {
+				weprintf("symlink %s -> %s:", s2, target);
 				cp_status = 1;
 				return 0;
 			}
 		}
-		goto preserve;
-	}
-
-	if (S_ISDIR(st.st_mode)) {
-		if (!cp_rflag)
-			eprintf("%s: is a directory\n", s1);
-
-		if (!(dp = opendir(s1)))
-			eprintf("opendir %s:", s1);
-
-		if (mkdir(s2, st.st_mode) < 0 && errno != EEXIST)
-			eprintf("mkdir %s:", s2);
+	} else if (S_ISDIR(st.st_mode)) {
+		if (!cp_rflag) {
+			weprintf("%s is a directory\n", s1);
+			cp_status = 1;
+			return 0;
+		}
+		if (!(dp = opendir(s1))) {
+			weprintf("opendir %s:", s1);
+			cp_status = 1;
+			return 0;
+		}
+		if (mkdir(s2, st.st_mode) < 0 && errno != EEXIST) {
+			weprintf("mkdir %s:", s2);
+			cp_status = 1;
+			return 0;
+		}
 
 		while ((d = readdir(dp))) {
-			if (strcmp(d->d_name, ".") && strcmp(d->d_name, "..")) {
-				r = snprintf(ns1, sizeof(ns1), "%s/%s", s1, d->d_name);
-				if (r >= sizeof(ns1) || r < 0) {
-					eprintf("%s/%s: filename too long\n",
-						s1, d->d_name);
-				}
-				r = snprintf(ns2, sizeof(ns2), "%s/%s", s2, d->d_name);
-				if (r >= sizeof(ns2) || r < 0) {
-					eprintf("%s/%s: filename too long\n",
-						s2, d->d_name);
-				}
-				fnck(ns1, ns2, cp, depth + 1);
-			}
+			if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
+				continue;
+
+			estrlcpy(ns1, s1, sizeof(ns1));
+			if(s1[strlen(s1) - 1] != '/')
+				estrlcat(ns1, "/", sizeof(ns1));
+			estrlcat(ns1, d->d_name, sizeof(ns1));
+
+			estrlcpy(ns2, s2, sizeof(ns2));
+			if(s2[strlen(s2) - 1] != '/')
+				estrlcat(ns2, "/", sizeof(ns2));
+			estrlcat(ns2, d->d_name, sizeof(ns2));
+
+			fnck(ns1, ns2, cp, depth + 1);
 		}
+
 		closedir(dp);
-		goto preserve;
-	}
-
-	if (cp_aflag) {
-		if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode) ||
-		    S_ISSOCK(st.st_mode) || S_ISFIFO(st.st_mode)) {
-			unlink(s2);
-			if (mknod(s2, st.st_mode, st.st_rdev) < 0) {
-				weprintf("%s: can't create '%s':", argv0, s2);
-				cp_status = 1;
-				return 0;
-			}
-			goto preserve;
+	} else if (cp_aflag && (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode) ||
+	           S_ISSOCK(st.st_mode) || S_ISFIFO(st.st_mode))) {
+		if (cp_fflag && unlink(s2) < 0 && errno != ENOENT) {
+			weprintf("unlink %s:", s2);
+			cp_status = 1;
+			return 0;
+		} else if (mknod(s2, st.st_mode, st.st_rdev) < 0) {
+			weprintf("mknod %s:", s2);
+			cp_status = 1;
+			return 0;
 		}
-	}
-
-	if (!(f1 = fopen(s1, "r"))) {
-		weprintf("fopen %s:", s1);
-		cp_status = 1;
-		return 0;
-	}
-
-	if (!(f2 = fopen(s2, "w"))) {
-		if (cp_fflag) {
-			unlink(s2);
-			if (!(f2 = fopen(s2, "w"))) {
+	} else {
+		if (!(f1 = fopen(s1, "r"))) {
+			weprintf("fopen %s:", s1);
+			cp_status = 1;
+			return 0;
+		}
+		if (!(f2 = fopen(s2, "w"))) {
+			if (cp_fflag) {
+				if (unlink(s2) < 0 && errno != ENOENT) {
+					weprintf("unlink %s:", s2);
+					cp_status = 1;
+					return 0;
+				} else if (!(f2 = fopen(s2, "w"))) {
+					weprintf("fopen %s:", s2);
+					cp_status = 1;
+					return 0;
+				}
+			} else {
 				weprintf("fopen %s:", s2);
 				cp_status = 1;
 				return 0;
 			}
-		} else {
-			weprintf("fopen %s:", s2);
+		}
+		concat(f1, s1, f2, s2);
+
+		/* preserve permissions by default */
+		fchmod(fileno(f2), st.st_mode);
+
+		if (fclose(f2) == EOF) {
+			weprintf("fclose %s:", s2);
+			cp_status = 1;
+			return 0;
+		}
+		if (fclose(f1) == EOF) {
+			weprintf("fclose %s:", s1);
 			cp_status = 1;
 			return 0;
 		}
 	}
-	concat(f1, s1, f2, s2);
-	/* preserve permissions by default */
-	fchmod(fileno(f2), st.st_mode);
-	fclose(f2);
-	fclose(f1);
 
-preserve:
 	if (cp_aflag || cp_pflag) {
-		if (!(S_ISLNK(st.st_mode))) {
-			/* timestamp */
+		/* timestamp and owner*/
+		if (!S_ISLNK(st.st_mode)) {
 			ut.actime = st.st_atime;
 			ut.modtime = st.st_mtime;
 			utime(s2, &ut);
-		}
-		/* preserve owner ? */
-		if (S_ISLNK(st.st_mode))
-			r = lchown(s2, st.st_uid, st.st_gid);
-		else
-			r = chown(s2, st.st_uid, st.st_gid);
-		if (r < 0) {
-			weprintf("cp: can't preserve ownership of '%s':", s2);
-			cp_status = 1;
+
+			if (chown(s2, st.st_uid, st.st_gid) < 0) {
+				weprintf("chown %s:", s2);
+				cp_status = 1;
+				return 0;
+			}
+		} else {
+			if (lchown(s2, st.st_uid, st.st_gid) < 0) {
+				weprintf("lchown %s:", s2);
+				cp_status = 1;
+				return 0;
+			}
 		}
 	}
+
 	return 0;
 }

mv.c

@@ -18,7 +18,7 @@ mv(const char *s1, const char *s2, int depth)
 		return (mv_status = 0);
 	if (errno == EXDEV) {
 		cp_aflag = cp_rflag = cp_pflag = 1;
-		cp_HLPflag = 'P';
+		cp_follow = 'P';
 		rm_rflag = 1;
 		cp(s1, s2, depth);
 		rm(s1, NULL, NULL, &r);