tmpl

commit 839d8742c8fe85d6cffd60c4d39853779c5a1e16
parent f1e6447562f8521696af876a0f7c7fe3c0dcd51b
Author: Louis Burda <quent.burda@gmail.com>
Date:   Sun, 18 Jun 2023 17:34:06 +0200

Read input file-line wise and fix UAF

Diffstat:
M
main.c
 | 
147
+++++++++++++++++++++++++++++++++++++------------------------------------------
D
test
 | 
10
----------

2 files changed, 69 insertions(+), 88 deletions(-)
diff --git a/main.c b/main.c
@@ -1,10 +1,10 @@
 #define _XOPEN_SOURCE 500
 
-#include <err.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
+#include <stdarg.h>
 #include <stdlib.h>
 
 enum {
@@ -24,9 +24,33 @@ struct var {
 	struct var *next;
 };
 
-struct var *vars, **vars_end;
+static struct var *vars = NULL;
+static struct var **vars_end = &vars;
 
-const char *
+static struct block stack[32] = { 0 };
+static int stack_top = 0;
+static size_t lineno = 0;
+
+static void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fputs("tmpl: ", stderr);
+	vfprintf(stderr, fmt, ap);
+	if (*fmt && fmt[strlen(fmt)-1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	} else {
+		fputc('\n', stderr);
+	}
+	va_end(ap);
+
+	exit(1);
+}
+
+static const char *
 getvar(const char *name)
 {
 	struct var *var;
@@ -39,18 +63,18 @@ getvar(const char *name)
 	return getenv(name);
 }
 
-void
+static void
 assign(char *line)
 {
 	char *sep;
 	struct var *var;
 
 	sep = strchr(line, '=');
-	if (!sep) err(1, "invalid assign: '%s'", line);
+	if (!sep) die("invalid assign '%s'", line);
 	*sep = '\0';
 
 	var = malloc(sizeof(struct var));
-	if (!var) err(1, "malloc");
+	if (!var) die("malloc:");
 	var->name = line;
 	var->value = sep + 1;
 	var->next = NULL;
@@ -59,20 +83,17 @@ assign(char *line)
 	vars_end = &var->next;
 }
 
-void
+static void
 template(char *line)
 {
-	static struct block stack[32] = { 0 };
-	static int stack_top = 0;
-	static size_t lineno = 0;
 	const char *value;
 	char *open, *close;
-	char *sep;
+	char *sep, *dup;
 
 	lineno++;
 
 	if (!strncmp(line, "#ifdef ", 7)) {
-		if (stack_top == 32) errx(1, "too much nesting");
+		if (stack_top == 32) die("too deeply nested");
 		stack[stack_top].active = 0;
 		stack[stack_top].type = IFDEF;
 		if (!stack_top || stack[stack_top-1].active) {
@@ -81,13 +102,13 @@ template(char *line)
 		}
 		stack_top++;
 	} else if (!strncmp(line, "#ifeq ", 6)) {
-		if (stack_top == 32) errx(1, "too much nesting");
+		if (stack_top == 32) die("too deeply nested");
 		stack[stack_top].active = 0;
 		stack[stack_top].type = IFEQ;
 		if (!stack_top || stack[stack_top-1].active) {
 			value = getvar(line + 6);
 			sep = strchr(line + 6, ' ');
-			if (!sep) err(1, "invalid #ifeq: %lu:%s", lineno, line);
+			if (!sep) die("invalid #ifeq\n%lu: %s", lineno, line);
 			if (!strcmp(value, sep + 1)) {
 				stack[stack_top].active = 1;
 			}
@@ -96,31 +117,35 @@ template(char *line)
 	} else if (!strcmp(line, "#else")) {
 		if (!stack_top || (stack[stack_top-1].type != IFDEF
 				&& stack[stack_top-1].type != IFEQ))
-			err(1, "invalid #else: %lu:%s", lineno, line);
+			die("invalid #else\n%lu: %s", lineno, line);
 		stack[stack_top-1].active ^= 1;
 		stack[stack_top-1].type = ELSE;
 	} else if (!strcmp(line, "#endif")) {
-		if (!stack_top) err(1, "invalid #endif: %lu:%s", lineno, line);
+		if (!stack_top) die("invalid #endif\n%lu: %s", lineno, line);
 		stack_top--;
 	} else if (!strncmp(line, "#define ", 8)) {
 		if (stack_top && !stack[stack_top-1].active)
 			return;
 
 		sep = strchr(line + 8, ' ');
-		if (!sep) err(1, "invalid #default: %lu:%s", lineno, line);
+		if (!sep) die("invalid #default\n%lu: %s", lineno, line);
 		*sep = '=';
-		assign(line + 8);
+		dup = strdup(line + 8);
+		if (!dup) die("strdup:");
+		assign(dup);
 	} else if (!strncmp(line, "#default ", 9)) {
 		if (stack_top && !stack[stack_top-1].active)
 			return;
 
 		sep = strchr(line + 9, ' ');
-		if (!sep) err(1, "invalid #default: %lu:%s", lineno, line);
+		if (!sep) die("invalid #default\n%lu: %s", lineno, line);
 		*sep = '\0';
 		value = getvar(line + 9);
 		if (!value) {
 			*sep = '=';
-			assign(line + 9);
+			dup = strdup(line + 9);
+			if (!dup) die("strdup:");
+			assign(dup);
 		}
 	} else if (!strncmp(line, "#-- ", 4)) {
 		return; /* comment */
@@ -157,76 +182,44 @@ template(char *line)
 	}
 }
 
-void
-perline(char *contents, int nonempty, void (*process)(char *))
-{
-	char *line, *sep, *end;
-
-	line = contents;
-	do {
-		sep = strchr(line, '\n');
-		end = sep ? sep : line + strlen(line);
-		*end = '\0';
-		if (!nonempty || end > line + 1)
-			process(line);
-		line = end + 1;
-	} while (sep);
-}
-
-char *
-readall(const char *path)
+static void
+perline(const char *path, int nonempty, void (*process)(char *))
 {
-	char buf[BUFSIZ];
-	char *contents;
-	ssize_t ret;
-	size_t len, cap;
-	int fd;
-
-	fd = open(path, O_RDONLY);
-	if (fd < 0) err(1, "open '%s'", path);
-
-	cap = BUFSIZ + 1;
-	contents = malloc(cap);
-	if (!contents) err(1, "malloc");
-
-	len = 0;
-	while ((ret = read(fd, buf, BUFSIZ)) > 0) {
-		if (len + (size_t) ret >= cap) {
-			cap *= 2;
-			contents = realloc(contents, cap);
-			if (!contents) err(1, "realloc");
+	char linebuf[4096];
+	size_t len;
+	FILE *f;
+
+	f = fopen(path, "r");
+	if (!f) die("fopen '%s':", path);
+	while (fgets(linebuf, 4096, f)) {
+		len = strlen(linebuf);
+		if (len && linebuf[len - 1] == '\n') {
+			linebuf[len - 1] = '\0';
+		} else if (len && !feof(f)) {
+			die("fgets '%s': line too long", path);
 		}
-		memcpy(contents + len, buf, (size_t) ret);
-		len += (size_t) ret;
+		if (len || !nonempty)
+			process(linebuf);
 	}
-	contents[len] = '\0';
-
-	return contents;
+	fclose(f);
 }
 
 int
-main(int argc, const char **argv)
+main(int argc, char **argv)
 {
-	const char **arg;
 	const char *path;
-	char *str, *contents;
-
-	vars = NULL;
-	vars_end = &vars;
+	char **arg;
 
 	if (!argc) return 1;
 	for (arg = argv + 1; *arg; arg++) {
 		if (!strcmp(*arg, "-h") || !strcmp(*arg, "--help")) {
-			fprintf(stderr, "Usage: tmpl [-c CONFIG].. [-D NAME=VALUE].. FILE..\n");
+			fprintf(stderr, "Usage: tmpl [-c CONFIG].. "
+				"[-D NAME=VALUE].. FILE..\n");
 			return 1;
 		} else if (!strcmp(*arg, "-D") || !strcmp(*arg, "--define")) {
-			str = strdup(*++arg);
-			if (!str) err(1, "strdup");
-			assign(str);
+			assign(*++arg);
 		} else if (!strcmp(*arg, "-c") || !strcmp(*arg, "--config")) {
-			contents = readall(*++arg);
-			perline(contents, 1, assign);
-			free(contents);
+			perline(*++arg, 1, assign);
 		} else {
 			break;
 		}
@@ -234,8 +227,6 @@ main(int argc, const char **argv)
 
 	for (; *arg; arg++) {
 		path = !strcmp(*arg, "-") ? "/dev/stdin" : *arg;
-		contents = readall(path);
-		perline(contents, 0, template);
-		free(contents);
+		perline(path, 0, template);
 	}
 }
diff --git a/test b/test
@@ -1,10 +0,0 @@
-#default PREFIX /usr/local
-#default BINDIR /bin
-
-#ifdef DEBUG
-yes debug
-#else
-no debug
-#endif
-
-install -m755 "#{TARGET}" -t "#{DESTDIR}#{PREFIX}#{BINDIR}"