Add "size" argument to eio.fread()

Signed-off-by: Tobias Ulmer <tu@emlix.com>

diff --git a/generic/eio.lua b/generic/eio.lua
index d99c7e571c2ad5ec125757caa57ee9faeccb8cf2..48f77164b0d5522868dc4ee78f073f6d2acc2b2c 100644 (file)
--- a/generic/eio.lua
+++ b/generic/eio.lua
@@ -135,10 +135,11 @@ end
 
 --- Read a file.
 -- @param file File object.
--- @return File data as a string, or false on error. May be up to 16K bytes
--- large and contain embedded zero's. On EOF an empty string is returned.
+-- @param size Positive number specifying how many bytes to read.
+-- @return File data as a string, or false on error. May be *up to* 'size' bytes
+-- large and contain embedded zero's. On EOF the empty string is returned.
 -- @return Error object on failure.
-function eio.fread(file)
+function eio.fread(file, size)
     local rc, re, errstring, buffer
 
     rc, re = is_eio_object(file)
@@ -146,7 +147,15 @@ function eio.fread(file)
         return false, re
     end
 
-    buffer, errstring = leio.fread(file.handle)
+    if type(size) ~= "number" then
+        return false, err.new("error reading file: size argument has wrong type")
+    end
+
+    if size <= 0 or size > 2147483648 --[[2GB]] then
+        return false, err("error reading file: size argument out of range")
+    end
+
+    buffer, errstring = leio.fread(file.handle, size)
     if not buffer then
         return false, err.new("error reading file: %s", errstring)
     end

diff --git a/generic/leio.c b/generic/leio.c
index 2e7deea7810fe50c59a04c2dddd6a8494d75e2a0..e44cbe5cfaf02fb7891cc66042a200571ac3a736 100644 (file)
--- a/generic/leio.c
+++ b/generic/leio.c
@@ -148,36 +148,46 @@ eio_fwrite(lua_State *lua)
 static int
 eio_fread(lua_State *lua)
 {
-       char buf[16384];
-       size_t ret;
+       char *buf;
        FILE *f;
+       size_t ret, sz;
 
        f = lua_touserdata(lua, 1);
-       if (f == NULL) {
+       sz = lua_tointeger(lua, 2);
+       if (f == NULL || sz == 0) {
                lua_pushboolean(lua, 0);
                lua_pushstring(lua,
                    "eio_fread: one or more arguments of wrong type/missing");
                return 2;
        }
 
+       buf = malloc(sz);
+       if (buf == NULL) {
+               lua_pushboolean(lua, 0);
+               lua_pushstring(lua, strerror(errno));
+               return 2;
+       }
 
-       ret = fread(buf, 1, sizeof(buf), f);
-       if (ret != sizeof(buf)) {
+       ret = fread(buf, 1, sz, f);
+       if (ret != sz) {
                if (ferror(f)) {
-                   lua_pushboolean(lua, 0);
-                   lua_pushstring(lua, strerror(errno));
-                   return 2;
+                       free(buf);
+                       lua_pushboolean(lua, 0);
+                       lua_pushstring(lua, strerror(errno));
+                       return 2;
                }
 
                if (ret <= 0 && feof(f)) {
                        /* ret <= 0: do not discard data on short reads,
                         * only signal EOF when all data is returned. */
+                       free(buf);
                        lua_pushstring(lua, "");
                        return 1;
                }
        }
 
        lua_pushlstring(lua, buf, ret);
+       free(buf);
        return 1;
 }