infra: make string allocation fully dynamic

kernel/sy_old/mars_light.c

@@ -157,6 +157,8 @@ EXPORT_SYMBOL_GPL(mars_reset_emergency);
 int mars_keep_msg = 10;
 EXPORT_SYMBOL_GPL(mars_keep_msg);
 
+#define MARS_SYMLINK_MAX 1023
+
 struct key_value_pair {
         const char *key;
         char *val;

kernel/sy_old/strategy.h

@@ -8,8 +8,6 @@
 #include "../mars.h"
 
 #define MARS_ARGV_MAX 4
-#define MARS_PATH_MAX 256
-#define MARS_SYMLINK_MAX 1023
 
 extern loff_t global_total_space;
 extern loff_t global_remaining_space;

kernel/sy_old/sy_generic.c

@@ -65,6 +65,20 @@ EXPORT_SYMBOL_GPL(mars_dent_meta);
 
 // some helpers
 
+static inline
+int _length_paranoia(int len, int line)
+{
+	if (unlikely(len < 0)) {
+		MARS_ERR("implausible string length %d (line=%d)\n", len, line);
+		len = PAGE_SIZE - 2;
+	} else if (unlikely(len > PAGE_SIZE - 2)) {
+		MARS_WRN("string length %d will be truncated to %d (line=%d)\n",
+			 len, (int)PAGE_SIZE - 2, line);
+		len = PAGE_SIZE - 2;
+	}
+	return len;
+}
+
 int mars_stat(const char *path, struct kstat *stat, bool use_lstat)
 {
 	mm_segment_t oldfs;
@@ -549,6 +563,7 @@ int get_inode(char *newpath, struct mars_dent *dent)
 			status = -EINVAL;
 			goto done;
 		}
+		len = _length_paranoia(len, __LINE__);
 
 		status = user_path_at(AT_FDCWD, newpath, 0, &path);
 		if (unlikely(status < 0)) {
@@ -559,14 +574,12 @@ int get_inode(char *newpath, struct mars_dent *dent)
                 inode = path.dentry->d_inode;
 
 		status = -ENOMEM;
-		link = brick_string_alloc(0);
+		link = brick_string_alloc(len + 2);
-		if (likely(link)) {
 		MARS_IO("len = %d\n", len);
 		status = inode->i_op->readlink(path.dentry, link, len + 1);
 		link[len] = '\0';
 		if (status < 0 ||
 		    (dent->new_link && !strncmp(dent->new_link, link, len))) {
-				//MARS_IO("symlink no change '%s' -> '%s' (%s) status = %d\n", newpath, link, dent->new_link ? dent->new_link : "", status);
 			brick_string_free(link);
 		} else {
 			MARS_IO("symlink '%s' -> '%s' (%s) status = %d\n", newpath, link, dent->new_link ? dent->new_link : "", status);
@@ -574,7 +587,6 @@ int get_inode(char *newpath, struct mars_dent *dent)
 			dent->old_link = dent->new_link;
 			dent->new_link = link;
 		}
-		}
 		path_put(&path);
 	}
 
@@ -1421,11 +1433,18 @@ EXPORT_SYMBOL_GPL(mars_kill_brick_when_possible);
 
 char *_vpath_make(int line, const char *fmt, va_list *args)
 {
-	char *res = _brick_string_alloc(MARS_SYMLINK_MAX, line);
+	va_list copy_args;
+	char dummy[2];
+	int len;
+	char *res;
+
+	memcpy(&copy_args, args, sizeof(copy_args));
+	len = vsnprintf(dummy, sizeof(dummy), fmt, copy_args);
+	len = _length_paranoia(len, line);
+	res = _brick_string_alloc(len + 2, line);
+
+	vsnprintf(res, len + 1, fmt, *args);
 
-	if (likely(res)) {
-		vsnprintf(res, MARS_SYMLINK_MAX, fmt, *args);
-	}
 	return res;
 }
 EXPORT_SYMBOL_GPL(_vpath_make);
@@ -1444,12 +1463,23 @@ EXPORT_SYMBOL_GPL(_path_make);
 char *_backskip_replace(int line, const char *path, char delim, bool insert, const char *fmt, ...)
 {
 	int path_len = strlen(path);
-	int total_len = strlen(fmt) + path_len + MARS_SYMLINK_MAX;
+	int fmt_len;
-	char *res = _brick_string_alloc(total_len + 1, line);
+	int total_len;
-	if (likely(res)) {
+	char *res;
 	va_list args;
 	int pos = path_len;
 	int plus;
+	char dummy[2];
+
+	va_start(args, fmt);
+	fmt_len = vsnprintf(dummy, sizeof(dummy), fmt, args);
+	va_end(args);
+	fmt_len = _length_paranoia(fmt_len, line);
+
+	total_len = fmt_len + path_len;
+	total_len = _length_paranoia(total_len, line);
+
+	res = _brick_string_alloc(total_len + 2, line);
 
 	while (pos > 0 && path[pos] != '/') {
 		pos--;
@@ -1468,7 +1498,6 @@ char *_backskip_replace(int line, const char *path, char delim, bool insert, con
 	if (insert) {
 		strncpy(res + pos + plus, path + pos + 1, total_len - pos - plus);
 	}
-	}
 	return res;
 }
 EXPORT_SYMBOL_GPL(_backskip_replace);

userspace/marsadm

@@ -51,6 +51,7 @@ my $user_version = 0.1;
 my $mars = "/mars";
 my $host = `uname -n` or ldie "cannot determine my network node name\n";
 chomp $host;
+check_id($host);
 my $real_host = $host;
 my $force = 0;
 my $timeout = -1;
@@ -319,16 +320,25 @@ sub wait_cluster {
 ##################################################################
 
 # syntactic checks
+# (also check for existence)
 
 sub check_id {
-  my $str = shift;
+  my ($str, $must_exist) = @_;
-  ldie "identifier '$str' has disallowed characters" unless $str =~ m/^[A-Za-z_][-A-Za-z0-9_]*$/;
+  ldie "identifier '$str' is empty" unless defined($str) && $str;
-  ldie "identifier '$str' is too long (only 16 chars allowed)" if length($str) > 16;
+  ldie "identifier '$str' has disallowed characters" unless $str =~ m/^[A-Za-z0-9_][-A-Za-z0-9_]*$/;
+  ldie "identifier '$str' is too long (only 63 chars supported according to RFC 1123)" if length($str) > 63;
+  if (defined($must_exist) && $must_exist) {
+    my $ip_path = "$mars/ips/ip-$str";
+    ldie "host '$str' does not exist in $mars/ips/" unless get_link($ip_path, 1);
+  }
 }
 
 sub check_id_list {
-  my $str = shift;
+  my ($str, $must_exist) = @_;
-  ldie "comma-separated list '$str' has disallowed characters" unless $str =~ m/^[A-Za-z_][-A-Za-z0-9_,]*$/;
+  ldie "comma-separated list '$str' has disallowed characters" unless $str =~ m/^[A-Za-z0-9_][-A-Za-z0-9_,]*$/;
+  foreach my $id (split(",", $str)) {
+    check_id($id, $must_exist);
+  }
 }
 
 ##################################################################
@@ -1015,6 +1025,7 @@ sub _writable {
 }
 
 sub _get_ip {
+  check_id($host);
   my $ip_path = "$mars/ips/ip-$host";
   if (my $from_link = get_link($ip_path, 2)) {
     lprint_stderr "Using IP '$from_link' from '$ip_path'\n";
@@ -1119,7 +1130,7 @@ sub set_connect_pref_list {
     lprint "$value\n";
     return;
   }
-  check_id_list($list);
+  check_id_list($list, 1);
   set_link($list, $dst);
 }
 
@@ -3805,6 +3816,7 @@ foreach my $arg (@ARGV) {
     $threshold = $arg;
     next;
   } elsif ($arg =~ s/--host\s*=\s*([-_A-Za-z0-9]+)/$1/) {
+    check_id($arg);
     ldie "host '$arg' does not exist in /mars/ips/ip-*\n" unless -l "/mars/ips/ip-$arg";
     if ($arg ne $host) {
       lprint "ATTENTION: acting as if I were host '$arg'\n";