X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/bfa5400d3e166e1acc25dbe0b7f1fdf74b272568..04f1c8e7049f071302dc8fe596487012f898dd08:/misc.c

diff --git a/misc.c b/misc.c
index 09e6db57..fea96a97 100644
--- a/misc.c
+++ b/misc.c
@@ -1,10 +1,48 @@
+/*
+ * Platform-independent routines shared between all PuTTY programs.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
+#include <limits.h>
 #include <ctype.h>
 #include <assert.h>
 #include "putty.h"
 
+/*
+ * Parse a string block size specification. This is approximately a
+ * subset of the block size specs supported by GNU fileutils:
+ *  "nk" = n kilobytes
+ *  "nM" = n megabytes
+ *  "nG" = n gigabytes
+ * All numbers are decimal, and suffixes refer to powers of two.
+ * Case-insensitive.
+ */
+unsigned long parse_blocksize(const char *bs)
+{
+    char *suf;
+    unsigned long r = strtoul(bs, &suf, 10);
+    if (*suf != '\0') {
+	while (isspace(*suf)) suf++;
+	switch (*suf) {
+	  case 'k': case 'K':
+	    r *= 1024ul;
+	    break;
+	  case 'm': case 'M':
+	    r *= 1024ul * 1024ul;
+	    break;
+	  case 'g': case 'G':
+	    r *= 1024ul * 1024ul * 1024ul;
+	    break;
+	  case '\0':
+	  default:
+	    break;
+	}
+    }
+    return r;
+}
+
 /* ----------------------------------------------------------------------
  * String handling routines.
  */
@@ -57,13 +95,46 @@ char *dupcat(const char *s1, ...)
 /*
  * Do an sprintf(), but into a custom-allocated buffer.
  * 
- * Irritatingly, we don't seem to be able to do this portably using
- * vsnprintf(), because there appear to be issues with re-using the
- * same va_list for two calls, and the excellent C99 va_copy is not
- * yet widespread. Bah. Instead I'm going to do a horrid, horrid
- * hack, in which I trawl the format string myself, work out the
- * maximum length of each format component, and resize the buffer
- * before printing it.
+ * Currently I'm doing this via vsnprintf. This has worked so far,
+ * but it's not good, because:
+ * 
+ *  - vsnprintf is not available on all platforms. There's an ifdef
+ *    to use `_vsnprintf', which seems to be the local name for it
+ *    on Windows. Other platforms may lack it completely, in which
+ *    case it'll be time to rewrite this function in a totally
+ *    different way.
+ * 
+ *  - technically you can't reuse a va_list like this: it is left
+ *    unspecified whether advancing a va_list pointer modifies its
+ *    value or something it points to, so on some platforms calling
+ *    vsnprintf twice on the same va_list might fail hideously. It
+ *    would be better to use the `va_copy' macro mandated by C99,
+ *    but that too is not yet ubiquitous.
+ * 
+ * The only `properly' portable solution I can think of is to
+ * implement my own format string scanner, which figures out an
+ * upper bound for the length of each formatting directive,
+ * allocates the buffer as it goes along, and calls sprintf() to
+ * actually process each directive. If I ever need to actually do
+ * this, some caveats:
+ * 
+ *  - It's very hard to find a reliable upper bound for
+ *    floating-point values. %f, in particular, when supplied with
+ *    a number near to the upper or lower limit of representable
+ *    numbers, could easily take several hundred characters. It's
+ *    probably feasible to predict this statically using the
+ *    constants in <float.h>, or even to predict it dynamically by
+ *    looking at the exponent of the specific float provided, but
+ *    it won't be fun.
+ * 
+ *  - Don't forget to _check_, after calling sprintf, that it's
+ *    used at most the amount of space we had available.
+ * 
+ *  - Fault any formatting directive we don't fully understand. The
+ *    aim here is to _guarantee_ that we never overflow the buffer,
+ *    because this is a security-critical function. If we see a
+ *    directive we don't know about, we should panic and die rather
+ *    than run any risk.
  */
 char *dupprintf(const char *fmt, ...)
 {
@@ -104,6 +175,29 @@ char *dupvprintf(const char *fmt, va_list ap)
     }
 }
 
+/*
+ * Read an entire line of text from a file. Return a buffer
+ * malloced to be as big as necessary (caller must free).
+ */
+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;
+}
+
 /* ----------------------------------------------------------------------
  * Base64 encoding routine. This is required in public-key writing
  * but also in HTTP proxy handling, so it's centralised here.
@@ -295,14 +389,21 @@ void mlog(char *file, int line)
 }
 #endif
 
-void *safemalloc(size_t size)
+void *safemalloc(size_t n, size_t size)
 {
     void *p;
+
+    if (n > INT_MAX / size) {
+	p = NULL;
+    } else {
+	size *= n;
 #ifdef MINEFIELD
-    p = minefield_c_malloc(size);
+	p = minefield_c_malloc(size);
 #else
-    p = malloc(size);
+	p = malloc(size);
 #endif
+    }
+
     if (!p) {
 	char str[200];
 #ifdef MALLOC_LOG
@@ -322,22 +423,29 @@ void *safemalloc(size_t size)
     return p;
 }
 
-void *saferealloc(void *ptr, size_t size)
+void *saferealloc(void *ptr, size_t n, size_t size)
 {
     void *p;
-    if (!ptr) {
+
+    if (n > INT_MAX / size) {
+	p = NULL;
+    } else {
+	size *= n;
+	if (!ptr) {
 #ifdef MINEFIELD
-	p = minefield_c_malloc(size);
+	    p = minefield_c_malloc(size);
 #else
-	p = malloc(size);
+	    p = malloc(size);
 #endif
-    } else {
+	} else {
 #ifdef MINEFIELD
-	p = minefield_c_realloc(ptr, size);
+	    p = minefield_c_realloc(ptr, size);
 #else
-	p = realloc(ptr, size);
+	    p = realloc(ptr, size);
 #endif
+	}
     }
+
     if (!p) {
 	char str[200];
 #ifdef MALLOC_LOG