Steven Schveighoffer wrote:
"Andrei Alexandrescu" wrote
Someone mentioned an old bug in std.file.read here:
http://www.reddit.com/r/programming/comments/7xnty/walter_bright_on_porting_d_to_the_mac/
Two programmers sent in patches for the function. Which is to be committed
and why? (Linux versions shown. Apologies for noisy line breaks.)
Implementation 2, save 1 bug:
[snip]
Aha, cool. Thanks for the info. I've adapted the code to still only use
one loop:
void[] read(string name)
{
immutable fd = std.c.linux.linux.open(toStringz(name), O_RDONLY);
cenforce(fd != -1, name);
scope(exit) std.c.linux.linux.close(fd);
struct_stat statbuf = void;
cenforce(std.c.linux.linux.fstat(fd, &statbuf) == 0, name);
immutable initialAlloc = statbuf.st_size
? (statbuf.st_size + 16) & 15
: 1024;
void[] result = GC.malloc(initialAlloc, GC.BlkAttr.NO_SCAN)
[0 .. initialAlloc];
scope(failure) delete result;
size_t size = 0;
for (;;)
{
immutable actual = std.c.linux.linux.read(fd, result.ptr + size,
result.length - size);
cenforce(actual != -1, name);
if (actual == 0) break;
size += actual;
if (size < result.length) continue;
auto newAlloc = size + 1024 * 4;
result = GC.realloc(result.ptr, newAlloc, GC.BlkAttr.NO_SCAN)
[0 .. newAlloc];
}
return result[0 .. size];
}
One more improvement suggested by Walter - I allocate a multiple of 16
because that's allocator's granularity.
Andrei
