From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sat, 3 Jun 2017 16:55:12 +0000 (+0000)
Subject: Introduce str_strip_prefix_len function and STR_STRIP_PREFIX macro
X-Git-Tag: v4.18~139
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1459d07f94289aeff0ee2474ea26ba5dfc6022ac;p=strace

Introduce str_strip_prefix_len function and STR_STRIP_PREFIX macro

Address proliferation of string prefix check implementations.

* defs.h (str_strip_prefix_len): New inline function.
(STR_STRIP_PREFIX): New macro.
* qualify.c (strip_prefix): Remove.
(parse_inject_token): Use STR_STRIP_PREFIX instead of strip_prefix.
(qualify): Use str_strip_prefix_len.
* socketutils.c (netlink_parse_response): Likewise.
* util.c (printfd): Likewise.
---

diff --git a/defs.h b/defs.h
index f731fa8c..3c8c5a76 100644
--- a/defs.h
+++ b/defs.h
@@ -511,6 +511,20 @@ string_to_uint_upto(const char *const str, unsigned int max_val)
 }
 extern int next_set_bit(const void *bit_array, unsigned cur_bit, unsigned size_bits);
 
+/*
+ * Returns STR if it does not start with PREFIX,
+ * or a pointer to the first char in STR after PREFIX.
+ * The length of PREFIX is specified by PREFIX_LEN.
+ */
+static inline const char *
+str_strip_prefix_len(const char *str, const char *prefix, size_t prefix_len)
+{
+	return strncmp(str, prefix, prefix_len) ? str : str + prefix_len;
+}
+
+#define STR_STRIP_PREFIX(str, prefix)	\
+	str_strip_prefix_len((str), (prefix), sizeof(prefix) - 1)
+
 #define QUOTE_0_TERMINATED                      0x01
 #define QUOTE_OMIT_LEADING_TRAILING_QUOTES      0x02
 #define QUOTE_OMIT_TRAILING_0                   0x08
diff --git a/qualify.c b/qualify.c
index 30888e61..de1141d6 100644
--- a/qualify.c
+++ b/qualify.c
@@ -414,18 +414,6 @@ handle_inversion:
 	}
 }
 
-/*
- * Returns NULL if STR does not start with PREFIX,
- * or a pointer to the first char in STR after PREFIX.
- */
-static const char *
-strip_prefix(const char *prefix, const char *str)
-{
-	size_t len = strlen(prefix);
-
-	return strncmp(prefix, str, len) ? NULL : str + len;
-}
-
 static int
 find_errno_by_name(const char *name)
 {
@@ -446,7 +434,7 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
 	const char *val;
 	int intval;
 
-	if ((val = strip_prefix("when=", token))) {
+	if ((val = STR_STRIP_PREFIX(token, "when=")) != token) {
 		/*
 		 * 	== 1+1
 		 * F	== F+0
@@ -476,7 +464,7 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
 			/* F == F+0 */
 			fopts->step = 0;
 		}
-	} else if ((val = strip_prefix("error=", token))) {
+	} else if ((val = STR_STRIP_PREFIX(token, "error=")) != token) {
 		if (fopts->rval != INJECT_OPTS_RVAL_DEFAULT)
 			return false;
 		intval = string_to_uint_upto(val, MAX_ERRNO_VALUE);
@@ -485,14 +473,16 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
 		if (intval < 1)
 			return false;
 		fopts->rval = -intval;
-	} else if (!fault_tokens_only && (val = strip_prefix("retval=", token))) {
+	} else if (!fault_tokens_only
+		   && (val = STR_STRIP_PREFIX(token, "retval=")) != token) {
 		if (fopts->rval != INJECT_OPTS_RVAL_DEFAULT)
 			return false;
 		intval = string_to_uint(val);
 		if (intval < 0)
 			return false;
 		fopts->rval = intval;
-	} else if (!fault_tokens_only && (val = strip_prefix("signal=", token))) {
+	} else if (!fault_tokens_only
+		   && (val = STR_STRIP_PREFIX(token, "signal=")) != token) {
 		intval = sigstr_to_uint(val);
 		if (intval < 1 || intval > NSIG_BYTES * 8)
 			return false;
@@ -677,14 +667,14 @@ qualify(const char *str)
 	unsigned int i;
 
 	for (i = 0; i < ARRAY_SIZE(qual_options); ++i) {
-		const char *p = qual_options[i].name;
-		unsigned int len = strlen(p);
+		const char *name = qual_options[i].name;
+		const size_t len = strlen(name);
+		const char *val = str_strip_prefix_len(str, name, len);
 
-		if (strncmp(str, p, len) || str[len] != '=')
+		if (val == str || *val != '=')
 			continue;
-
+		str = val + 1;
 		opt = &qual_options[i];
-		str += len + 1;
 		break;
 	}
 
diff --git a/socketutils.c b/socketutils.c
index ef8269ce..534c56eb 100644
--- a/socketutils.c
+++ b/socketutils.c
@@ -381,12 +381,7 @@ netlink_parse_response(const char *proto_name, const void *data,
 				diag_msg->ndiag_protocol);
 
 	if (netlink_proto) {
-		static const char netlink_prefix[] = "NETLINK_";
-		const size_t netlink_prefix_len =
-			sizeof(netlink_prefix) -1;
-		if (strncmp(netlink_proto, netlink_prefix,
-			    netlink_prefix_len) == 0)
-			netlink_proto += netlink_prefix_len;
+		netlink_proto = STR_STRIP_PREFIX(netlink_proto, "NETLINK_");
 		if (asprintf(&details, "%s:[%s:%u]", proto_name,
 			     netlink_proto, diag_msg->ndiag_portid) < 0)
 			return -1;
diff --git a/util.c b/util.c
index 9b1c411d..50334b4f 100644
--- a/util.c
+++ b/util.c
@@ -635,17 +635,15 @@ printfd(struct tcb *tcp, int fd)
 {
 	char path[PATH_MAX + 1];
 	if (show_fd_path && getfdpath(tcp, fd, path, sizeof(path)) >= 0) {
-		static const char socket_prefix[] = "socket:[";
-		const size_t socket_prefix_len = sizeof(socket_prefix) - 1;
-		const size_t path_len = strlen(path);
+		const char *str;
+		size_t len;
+		unsigned long inode;
 
 		tprintf("%d<", fd);
-		if (show_fd_path > 1 &&
-		    strncmp(path, socket_prefix, socket_prefix_len) == 0 &&
-		    path[path_len - 1] == ']') {
-			unsigned long inode =
-				strtoul(path + socket_prefix_len, NULL, 10);
-
+		if (show_fd_path > 1
+		    && (str = STR_STRIP_PREFIX(path, "socket:[")) != path
+		    && (len = strlen(str)) && str[len - 1] == ']'
+		    && (inode = strtoul(str, NULL, 10))) {
 			if (!print_sockaddr_by_inode_cached(inode)) {
 				const enum sock_proto proto =
 					getfdproto(tcp, fd);
@@ -653,7 +651,7 @@ printfd(struct tcb *tcp, int fd)
 					tprints(path);
 			}
 		} else {
-			print_quoted_string(path, path_len,
+			print_quoted_string(path, strlen(path),
 					    QUOTE_OMIT_LEADING_TRAILING_QUOTES);
 		}
 		tprints(">");