Remove dangerous mg_pfn_realloc(). Add %q printf specifier

docs/README.md

@@ -2623,6 +2623,7 @@ Supported format specifiers:
 - `hhu`, `hu`, `u`, `lu`, `llu` - same but for unsigned variants
 - `hhx`, `hx`, `x`, `lx`, `llx` - same, unsigned and hex output
 - `s` - expect `char *`
+- `q` - expect `char *`, outputs JSON-escaped string (extension)
 - `Q` - expect `char *`, outputs double-quoted JSON-escaped string (extension)
 - `H` - expect `int`, `void *`, outputs double-quoted hex string (extension)
 - `V` - expect `int`, `void *`, outputs double-quoted base64 string (extension)
@@ -2736,28 +2737,6 @@ void myfn(char c, void *p);
 size_t len = mg_rprintf(myfn, myfn_p, "Double quoted string: %Q!", "hi");
 ```
 
-### mg\_pfn\_realloc()
-
-```c
-void mg_pfn_realloc(char ch, void *param);
-```
-
-Print a character to a malloced str
-
-Parameters:
-- `ch` - char to be printed
-- `param` - Pointer to a `char *`. Memory for the buffer will be reallocated to fit the new char
-
-Usage example:
-
-```c
-char *s = NULL;
-
-mg_rprintf(mg_pfn_realloc, &s, "Hello, %s", world);  // s == "Hello, world"
-mg_rprintf(mg_pfn_realloc, &s, "!");                 // s == "Hello, world!"
-free(s);
-```
-
 ### mg\_pfn\_iobuf()
 
 ```c
@@ -2768,12 +2747,12 @@ Print a character to a [Generic IO buffer](#struct-mg_iobuf)
 
 Parameters:
 - `ch` - char to be printed
-- `param` - pointer to a struct mg_iobuf
+- `param` - must be `struct mg_iobuf *`
 
 Usage example:
 
 ```c
-mg_rprintf(mg_pfn_iobuf, &c->send, "hi!");
+mg_rprintf(mg_pfn_iobuf, &c->send, "hi!");  // Append to the output buffer
 ```
 
 ### mg\_to64()

examples/device-dashboard/packed_fs.c

@@ -2795,11 +2795,11 @@ static const struct packed_file {
   size_t size;
   time_t mtime;
 } packed_files[] = {
-  {"/web_root/index.html", v1, sizeof(v1), 1654437619},
-  {"/web_root/main.js", v2, sizeof(v2), 1656444283},
-  {"/web_root/preact.min.js", v3, sizeof(v3), 1652374364},
-  {"/web_root/style.css", v4, sizeof(v4), 1654709515},
-  {"/web_root/user.png", v5, sizeof(v5), 1626172939},
+  {"/web_root/index.html", v1, sizeof(v1), 1659483223},
+  {"/web_root/main.js", v2, sizeof(v2), 1659483223},
+  {"/web_root/preact.min.js", v3, sizeof(v3), 1659483223},
+  {"/web_root/style.css", v4, sizeof(v4), 1659483223},
+  {"/web_root/user.png", v5, sizeof(v5), 1659483223},
   {NULL, NULL, 0, 0}
 };
 

examples/json-rpc-over-websocket/main.c

@@ -45,11 +45,11 @@ static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
   } else if (ev == MG_EV_WS_MSG) {
     // Got websocket frame. Received data is wm->data
     struct mg_ws_message *wm = (struct mg_ws_message *) ev_data;
-    char *resp = NULL;
-    struct mg_rpc_req r = {&s_rpc_head, 0, mg_pfn_realloc, &resp, 0, wm->data};
+    struct mg_iobuf io = {0, 0, 0, 512};
+    struct mg_rpc_req r = {&s_rpc_head, 0, mg_pfn_iobuf, &io, 0, wm->data};
     mg_rpc_process(&r);
-    if (resp) mg_ws_send(c, resp, strlen(resp), WEBSOCKET_OP_TEXT);
-    free(resp);
+    if (io.buf) mg_ws_send(c, (char *) io.buf, io.len, WEBSOCKET_OP_TEXT);
+    mg_iobuf_free(&io);
   }
   (void) fn_data;
 }

mongoose.c

@@ -494,20 +494,6 @@ void mg_pfn_iobuf(char ch, void *param) {
   }
 }
 
-// We don't use realloc() in mongoose, so resort to inefficient calloc
-// Every new character reallocates the whole string
-void mg_pfn_realloc(char ch, void *param) {
-  char *s, *buf = *(char **) param;
-  size_t len = buf == NULL ? 0 : strlen(buf);
-  if ((s = (char *) calloc(1, len + 2)) != NULL) {
-    if (buf != NULL) memcpy(s, buf, len);
-    s[len] = ch;
-    s[len + 1] = '\0';
-    free(buf);
-    *(char **) param = s;
-  }
-}
-
 size_t mg_vsnprintf(char *buf, size_t len, const char *fmt, va_list *ap) {
   struct mg_iobuf io = {(uint8_t *) buf, len, 0, 0};
   size_t n = mg_vrprintf(mg_putchar_iobuf_static, &io, fmt, ap);
@@ -697,8 +683,7 @@ static char mg_escape(int c) {
 
 static size_t qcpy(void (*out)(char, void *), void *ptr, char *buf,
                    size_t len) {
-  size_t i = 0, extra = 2;
-  out('"', ptr);
+  size_t i = 0, extra = 0;
   for (i = 0; i < len && buf[i] != '\0'; i++) {
     char c = mg_escape(buf[i]);
     if (c) {
@@ -707,10 +692,18 @@ static size_t qcpy(void (*out)(char, void *), void *ptr, char *buf,
       out(buf[i], ptr);
     }
   }
-  out('"', ptr);
   return i + extra;
 }
 
+static size_t Qcpy(void (*out)(char, void *), void *ptr, char *buf,
+                   size_t len) {
+  size_t n = 2;
+  out('"', ptr);
+  n += qcpy(out, ptr, buf, len);
+  out('"', ptr);
+  return n;
+}
+
 static size_t bcpy(void (*out)(char, void *), void *ptr, uint8_t *buf,
                    size_t len) {
   size_t i, n = 0;
@@ -807,10 +800,11 @@ size_t mg_vrprintf(void (*out)(char, void *), void *param, const char *fmt,
         size_t len = (size_t) va_arg(*ap, int);
         uint8_t *buf = va_arg(*ap, uint8_t *);
         n += bcpy(out, param, buf, len);
-      } else if (c == 's' || c == 'Q') {
+      } else if (c == 's' || c == 'Q' || c == 'q') {
         char *p = va_arg(*ap, char *);
-        size_t (*f)(void (*)(char, void *), void *, char *, size_t) =
-            c == 's' ? scpy : qcpy;
+        size_t (*f)(void (*)(char, void *), void *, char *, size_t) = scpy;
+        if (c == 'Q') f = Qcpy;
+        if (c == 'q') f = qcpy;
         if (pr == ~0U) pr = p == NULL ? 0 : strlen(p);
         for (j = 0; !minus && pr < w && j + pr < w; j++)
           n += f(out, param, &pad, 1);

mongoose.h

@@ -785,8 +785,7 @@ char *mg_remove_double_dots(char *s);
 
 typedef void (*mg_pfn_t)(char, void *);                  // Custom putchar
 typedef size_t (*mg_pm_t)(mg_pfn_t, void *, va_list *);  // %M printer
-void mg_pfn_realloc(char ch, void *param);  // Print to malloced str
-void mg_pfn_iobuf(char ch, void *param);    // Print to iobuf
+void mg_pfn_iobuf(char ch, void *param);                 // iobuf printer
 
 size_t mg_lld(char *buf, int64_t val, bool is_signed, bool is_hex);
 double mg_atod(const char *buf, int len, int *numlen);

src/fmt.c

@@ -82,20 +82,6 @@ void mg_pfn_iobuf(char ch, void *param) {
   }
 }
 
-// We don't use realloc() in mongoose, so resort to inefficient calloc
-// Every new character reallocates the whole string
-void mg_pfn_realloc(char ch, void *param) {
-  char *s, *buf = *(char **) param;
-  size_t len = buf == NULL ? 0 : strlen(buf);
-  if ((s = (char *) calloc(1, len + 2)) != NULL) {
-    if (buf != NULL) memcpy(s, buf, len);
-    s[len] = ch;
-    s[len + 1] = '\0';
-    free(buf);
-    *(char **) param = s;
-  }
-}
-
 size_t mg_vsnprintf(char *buf, size_t len, const char *fmt, va_list *ap) {
   struct mg_iobuf io = {(uint8_t *) buf, len, 0, 0};
   size_t n = mg_vrprintf(mg_putchar_iobuf_static, &io, fmt, ap);
@@ -285,8 +271,7 @@ static char mg_escape(int c) {
 
 static size_t qcpy(void (*out)(char, void *), void *ptr, char *buf,
                    size_t len) {
-  size_t i = 0, extra = 2;
-  out('"', ptr);
+  size_t i = 0, extra = 0;
   for (i = 0; i < len && buf[i] != '\0'; i++) {
     char c = mg_escape(buf[i]);
     if (c) {
@@ -295,10 +280,18 @@ static size_t qcpy(void (*out)(char, void *), void *ptr, char *buf,
       out(buf[i], ptr);
     }
   }
-  out('"', ptr);
   return i + extra;
 }
 
+static size_t Qcpy(void (*out)(char, void *), void *ptr, char *buf,
+                   size_t len) {
+  size_t n = 2;
+  out('"', ptr);
+  n += qcpy(out, ptr, buf, len);
+  out('"', ptr);
+  return n;
+}
+
 static size_t bcpy(void (*out)(char, void *), void *ptr, uint8_t *buf,
                    size_t len) {
   size_t i, n = 0;
@@ -395,10 +388,11 @@ size_t mg_vrprintf(void (*out)(char, void *), void *param, const char *fmt,
         size_t len = (size_t) va_arg(*ap, int);
         uint8_t *buf = va_arg(*ap, uint8_t *);
         n += bcpy(out, param, buf, len);
-      } else if (c == 's' || c == 'Q') {
+      } else if (c == 's' || c == 'Q' || c == 'q') {
         char *p = va_arg(*ap, char *);
-        size_t (*f)(void (*)(char, void *), void *, char *, size_t) =
-            c == 's' ? scpy : qcpy;
+        size_t (*f)(void (*)(char, void *), void *, char *, size_t) = scpy;
+        if (c == 'Q') f = Qcpy;
+        if (c == 'q') f = qcpy;
         if (pr == ~0U) pr = p == NULL ? 0 : strlen(p);
         for (j = 0; !minus && pr < w && j + pr < w; j++)
           n += f(out, param, &pad, 1);

src/fmt.h

@@ -5,8 +5,7 @@
 
 typedef void (*mg_pfn_t)(char, void *);                  // Custom putchar
 typedef size_t (*mg_pm_t)(mg_pfn_t, void *, va_list *);  // %M printer
-void mg_pfn_realloc(char ch, void *param);  // Print to malloced str
-void mg_pfn_iobuf(char ch, void *param);    // Print to iobuf
+void mg_pfn_iobuf(char ch, void *param);                 // iobuf printer
 
 size_t mg_lld(char *buf, int64_t val, bool is_signed, bool is_hex);
 double mg_atod(const char *buf, int len, int *numlen);

test/unit_test.c

@@ -1469,13 +1469,19 @@ static void test_str(void) {
 
   // Non-standard formatting
   {
-    char buf[100], *p;
+    char buf[100], *p = NULL;
+    struct mg_iobuf io = {0, 0, 0, 16};
     const char *expected;
 
     expected = "\"\"";
     mg_snprintf(buf, sizeof(buf), "%Q", "");
     ASSERT(strcmp(buf, expected) == 0);
 
+    expected = "\"hi, \\\"\"";
+    mg_snprintf(buf, sizeof(buf), "\"hi, %q\"", "\"");
+    MG_INFO(("[%s] [%s]", buf, expected));
+    ASSERT(strcmp(buf, expected) == 0);
+
     expected = "\"a'b\"";
     mg_snprintf(buf, sizeof(buf), "%Q", "a'b");
     ASSERT(strcmp(buf, expected) == 0);
@@ -1497,12 +1503,12 @@ static void test_str(void) {
     ASSERT(strcmp(p, "[9876543210,7]") == 0);
     free(p);
 
-    p = mg_mprintf("[%M", pf2, 10);
-    mg_rprintf(mg_pfn_realloc, &p, ",");
-    mg_rprintf(mg_pfn_realloc, &p, "%d]", 7);
-    printf("-> %s\n", p);
-    ASSERT(strcmp(p, "[9876543210,7]") == 0);
-    free(p);
+    mg_rprintf(mg_pfn_iobuf, &io, "[%M", pf2, 10);
+    mg_rprintf(mg_pfn_iobuf, &io, ",");
+    mg_rprintf(mg_pfn_iobuf, &io, "%d]", 7);
+    printf("-> %s\n", io.buf);
+    ASSERT(strcmp((char *) io.buf, "[9876543210,7]") == 0);
+    mg_iobuf_free(&io);
   }
 
   {
@@ -2450,23 +2456,22 @@ static void test_json(void) {
 
 static void test_rpc(void) {
   struct mg_rpc *head = NULL;
-  char *s = NULL;
-  struct mg_rpc_req req = {&head, 0, mg_pfn_realloc, &s, 0, {0, 0}};
+  struct mg_iobuf io = {0, 0, 0, 256};
+  struct mg_rpc_req req = {&head, 0, mg_pfn_iobuf, &io, 0, {0, 0}};
   mg_rpc_add(&head, mg_str("rpc.list"), mg_rpc_list, NULL);
 
   {
     req.frame = mg_str("{\"method\":\"rpc.list\"}");
     mg_rpc_process(&req);
-    ASSERT(s == NULL);
+    ASSERT(io.buf == NULL);
   }
 
   {
     const char *resp = "{\"id\":1,\"result\":[\"rpc.list\"]}";
     req.frame = mg_str("{\"id\": 1,\"method\":\"rpc.list\"}");
     mg_rpc_process(&req);
-    MG_INFO(("-> %s", s));
-    ASSERT(strcmp(s, resp) == 0);
-    free(s), s = NULL;
+    ASSERT(strcmp((char *) io.buf, resp) == 0);
+    mg_iobuf_free(&io);
   }
 
   {
@@ -2475,18 +2480,17 @@ static void test_rpc(void) {
         "found\"}}";
     req.frame = mg_str("{\"id\": true,\"method\":\"foo\"}");
     mg_rpc_process(&req);
-    MG_INFO(("-> %s", s));
-    ASSERT(strcmp(s, resp) == 0);
-    free(s), s = NULL;
+    // MG_INFO(("-> %s", io.buf));
+    ASSERT(strcmp((char *) io.buf, resp) == 0);
+    mg_iobuf_free(&io);
   }
 
   {
     const char *resp = "{\"error\":{\"code\":-32700,\"message\":\"haha\"}}";
     req.frame = mg_str("haha");
     mg_rpc_process(&req);
-    MG_INFO(("-> %s", s));
-    ASSERT(strcmp(s, resp) == 0);
-    free(s), s = NULL;
+    ASSERT(strcmp((char *) io.buf, resp) == 0);
+    mg_iobuf_free(&io);
   }
 
   mg_rpc_del(&head, NULL);