load: Check for integer and real overlfows and underflows

[jansson.git] / src / load.c

diff --git a/src/load.c b/src/load.c
index 975d7e9..5175f35 100644 (file)
--- a/src/load.c
+++ b/src/load.c
@@ -1,6 +1,14 @@
+/*
+ * Copyright (c) 2009 Petri Lehtinen <petri@digip.org>
+ *
+ * Jansson is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
 #define _GNU_SOURCE
 #include <ctype.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -127,10 +135,7 @@ static char stream_get(stream_t *stream, json_error_t *error)
 
         c = stream->buffer[0];
 
-        if(c == EOF && stream->eof(stream->data))
-            return EOF;
-
-        if(c < 0)
+        if(c < 0 && c != EOF)
         {
             /* multi-byte UTF-8 sequence */
             int i, count;
@@ -250,11 +255,11 @@ static void lex_scan_string(lex_t *lex, json_error_t *error)
     lex->value.string = NULL;
     lex->token = TOKEN_INVALID;
 
-    /* skip the " */
     c = lex_get_save(lex, error);
 
     while(c != '"') {
         if(c == EOF) {
+            lex_unget_unsave(lex, c);
             if(lex_eof(lex))
                 error_set(error, lex, "premature end of input");
             goto out;
@@ -395,10 +400,11 @@ out:
     free(lex->value.string);
 }
 
-static void lex_scan_number(lex_t *lex, char c, json_error_t *error)
+static int lex_scan_number(lex_t *lex, char c, json_error_t *error)
 {
     const char *saved_text;
     char *end;
+    double value;
 
     lex->token = TOKEN_INVALID;
 
@@ -419,14 +425,26 @@ static void lex_scan_number(lex_t *lex, char c, json_error_t *error)
     }
 
     if(c != '.' && c != 'E' && c != 'e') {
+        long value;
+
         lex_unget_unsave(lex, c);
-        lex->token = TOKEN_INTEGER;
 
         saved_text = strbuffer_value(&lex->saved_text);
-        lex->value.integer = strtol(saved_text, &end, 10);
+        value = strtol(saved_text, &end, 10);
         assert(end == saved_text + lex->saved_text.length);
 
-        return;
+        if((value == LONG_MAX && errno == ERANGE) || value > INT_MAX) {
+            error_set(error, lex, "too big integer");
+            goto out;
+        }
+        else if((value == LONG_MIN && errno == ERANGE) || value < INT_MIN) {
+            error_set(error, lex, "too big negative integer");
+            goto out;
+        }
+
+        lex->token = TOKEN_INTEGER;
+        lex->value.integer = (int)value;
+        return 0;
     }
 
     if(c == '.') {
@@ -456,14 +474,29 @@ static void lex_scan_number(lex_t *lex, char c, json_error_t *error)
     }
 
     lex_unget_unsave(lex, c);
-    lex->token = TOKEN_REAL;
 
     saved_text = strbuffer_value(&lex->saved_text);
-    lex->value.real = strtod(saved_text, &end);
+    value = strtod(saved_text, &end);
     assert(end == saved_text + lex->saved_text.length);
 
+    if(value == 0 && errno == ERANGE) {
+        error_set(error, lex, "real number underflow");
+        goto out;
+    }
+
+    /* Cannot test for +/-HUGE_VAL because the HUGE_VAL constant is
+       only defined in C99 mode. So let's trust in sole errno. */
+    else if(errno == ERANGE) {
+        error_set(error, lex, "real number overflow");
+        goto out;
+    }
+
+    lex->token = TOKEN_REAL;
+    lex->value.real = value;
+    return 0;
+
 out:
-    return;
+    return -1;
 }
 
 static int lex_scan(lex_t *lex, json_error_t *error)
@@ -502,8 +535,10 @@ static int lex_scan(lex_t *lex, json_error_t *error)
     else if(c == '"')
         lex_scan_string(lex, error);
 
-    else if(isdigit(c) || c == '-')
-        lex_scan_number(lex, c, error);
+    else if(isdigit(c) || c == '-') {
+        if(lex_scan_number(lex, c, error))
+            goto out;
+    }
 
     else if(isupper(c) || islower(c)) {
         /* eat up the whole identifier for clearer error messages */
@@ -734,25 +769,6 @@ json_t *parse_json(lex_t *lex, json_error_t *error)
     return parse_value(lex, error);
 }
 
-json_t *json_load(const char *path, json_error_t *error)
-{
-    json_t *result;
-    FILE *fp;
-
-    fp = fopen(path, "r");
-    if(!fp)
-    {
-        error_set(error, NULL, "unable to open %s: %s",
-                  path, strerror(errno));
-        return NULL;
-    }
-
-    result = json_loadf(fp, error);
-
-    fclose(fp);
-    return result;
-}
-
 typedef struct
 {
     const char *data;
@@ -817,7 +833,36 @@ json_t *json_loadf(FILE *input, json_error_t *error)
         return NULL;
 
     result = parse_json(&lex, error);
+    if(!result)
+        goto out;
 
+    lex_scan(&lex, error);
+    if(lex.token != TOKEN_EOF) {
+        error_set(error, &lex, "end of file expected");
+        json_decref(result);
+        result = NULL;
+    }
+
+out:
     lex_close(&lex);
     return result;
 }
+
+json_t *json_load_file(const char *path, json_error_t *error)
+{
+    json_t *result;
+    FILE *fp;
+
+    fp = fopen(path, "r");
+    if(!fp)
+    {
+        error_set(error, NULL, "unable to open %s: %s",
+                  path, strerror(errno));
+        return NULL;
+    }
+
+    result = json_loadf(fp, error);
+
+    fclose(fp);
+    return result;
+}