gdImageStringFT() fails for empty strings as of libgd 2.3.0

[cmb69]

When trying to render an empty string via gdImageStringFT(), the function fails as of libgd 2.3.0, while formerly it was just a no-op.

Test script

#include <stdio.h>
#include <gd.h>

int main()
{
    gdImagePtr im;
    int fg;
    int rect[8];
    char *res;

    im = gdImageCreate(100, 100);
    fg = gdImageColorAllocate(im, 255, 255, 255);
    res = gdImageStringFT(im, rect, fg, "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf", 12, 0, 10, 10, "");
    if (res) printf("%s\n", res);
    return 0;
}

Expected output

okay

Actual output

Problem doing text layout

[cmb69]

Forwarded from https://bugs.php.net/79415.

[cmb69]

The problem is that textLayout() returns 0 to signal failure, but also if an empty string is passed, although the latter is not necessarily a failure.

[willson-chen]

I have no idea about how to fix this issue. Could your please offer some tips about the solution? @cmb69

[remicollet]

@cmb69 can you please have a look, it seems your patch is not enough, perhaps related to some library version.

gdImageStringFT fails with "Problem doing text layout"

[cmb69]

Is ssize_t and SSIZE_MAX available on that platform? Do you have a build with or without libraqm?

[remicollet]

Do you have a build with or without libraqm?

Yes, this is related to libraqm, see pr #649