X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/797f6ff3e6da533570a0dc074771d485619e49c8..39934deb5202149f98198c111a35c21cb4d0d0f8:/unix/uxstore.c

diff --git a/unix/uxstore.c b/unix/uxstore.c
index e12af036..c46b9a29 100644
--- a/unix/uxstore.c
+++ b/unix/uxstore.c
@@ -19,7 +19,7 @@
 #include "tree234.h"
 
 enum {
-    INDEX_DIR, INDEX_HOSTKEYS, INDEX_RANDSEED,
+    INDEX_DIR, INDEX_HOSTKEYS, INDEX_HOSTKEYS_TMP, INDEX_RANDSEED,
     INDEX_SESSIONDIR, INDEX_SESSION,
 };
 
@@ -98,42 +98,13 @@ static void make_filename(char *filename, int index, const char *subname)
                 index == INDEX_DIR ? "/.putty" :
                 index == INDEX_SESSIONDIR ? "/.putty/sessions" :
                 index == INDEX_HOSTKEYS ? "/.putty/sshhostkeys" :
+                index == INDEX_HOSTKEYS_TMP ? "/.putty/sshhostkeys.tmp" :
                 index == INDEX_RANDSEED ? "/.putty/randomseed" :
                 "/.putty/ERROR", FILENAME_MAX - len);
     }
     filename[FILENAME_MAX-1] = '\0';
 }
 
-/*
- * Read an entire line of text from a file. Return a buffer
- * malloced to be as big as necessary (caller must free).
- */
-static char *fgetline(FILE *fp)
-{
-    char *ret = snewn(512, char);
-    int size = 512, len = 0;
-    while (fgets(ret + len, size - len, fp)) {
-	len += strlen(ret + len);
-	if (ret[len-1] == '\n')
-	    break;		       /* got a newline, we're done */
-	size = len + 512;
-	ret = sresize(ret, size, char);
-    }
-    if (len == 0) {		       /* first fgets returned NULL */
-	sfree(ret);
-	return NULL;
-    }
-    ret[len] = '\0';
-    return ret;
-}
-
-/*
- * For the moment, the only existing Unix utility is pterm and that
- * has no GUI configuration at all, so our write routines need do
- * nothing. Eventually I suppose these will read and write an rc
- * file somewhere or other.
- */
-
 void *open_settings_w(const char *sessionname, char **errmsg)
 {
     char filename[FILENAME_MAX];
@@ -188,6 +159,7 @@ void close_settings_w(void *handle)
  * PuTTY's inbuilt defaults, but that the disk files will then
  * override those. This isn't optimal, but it's the best I can
  * immediately work out.
+ * FIXME: the above comment is a bit out of date. Did it happen?
  */
 
 struct keyval {
@@ -494,32 +466,60 @@ int verify_host_key(const char *hostname, int port,
 	    break;
     }
 
+    fclose(fp);
     return ret;
 }
 
 void store_host_key(const char *hostname, int port,
 		    const char *keytype, const char *key)
 {
-    FILE *fp;
-    int fd;
-    char filename[FILENAME_MAX];
+    FILE *rfp, *wfp;
+    char *newtext, *line;
+    int headerlen;
+    char filename[FILENAME_MAX], tmpfilename[FILENAME_MAX];
 
-    make_filename(filename, INDEX_HOSTKEYS, NULL);
-    fd = open(filename, O_CREAT | O_APPEND | O_RDWR, 0600);
-    if (fd < 0) {
-	char dir[FILENAME_MAX];
+    newtext = dupprintf("%s@%d:%s %s\n", keytype, port, hostname, key);
+    headerlen = 1 + strcspn(newtext, " ");   /* count the space too */
 
-	make_filename(dir, INDEX_DIR, NULL);
-	mkdir(dir, 0700);
-	fd = open(filename, O_CREAT | O_APPEND | O_RDWR, 0600);
+    /*
+     * Open both the old file and a new file.
+     */
+    make_filename(tmpfilename, INDEX_HOSTKEYS_TMP, NULL);
+    wfp = fopen(tmpfilename, "w");
+    if (!wfp) {
+        char dir[FILENAME_MAX];
+
+        make_filename(dir, INDEX_DIR, NULL);
+        mkdir(dir, 0700);
+        wfp = fopen(tmpfilename, "w");
     }
-    if (fd < 0) {
-	perror(filename);
-	exit(1);
+    if (!wfp)
+	return;
+    make_filename(filename, INDEX_HOSTKEYS, NULL);
+    rfp = fopen(filename, "r");
+
+    /*
+     * Copy all lines from the old file to the new one that _don't_
+     * involve the same host key identifier as the one we're adding.
+     */
+    if (rfp) {
+        while ( (line = fgetline(rfp)) ) {
+            if (strncmp(line, newtext, headerlen))
+                fputs(line, wfp);
+        }
+        fclose(rfp);
     }
-    fp = fdopen(fd, "a");
-    fprintf(fp, "%s@%d:%s %s\n", keytype, port, hostname, key);
-    fclose(fp);
+
+    /*
+     * Now add the new line at the end.
+     */
+    fputs(newtext, wfp);
+
+    fclose(wfp);
+
+    rename(tmpfilename, filename);
+
+    sfree(newtext);
 }
 
 void read_random_seed(noise_consumer_t consumer)