no-reply@allegro.cc (nshade) — Mon, 19 Nov 2018 00:31:49 +0000

I think I have a test case here. When reading in data from a file, allegro is randomly pushing the read index ahead one.

Here is the output from reading a zip file with no compression.

Quote:

Got Header
Read in 4 bytes After header, now at 4
Skipped ahead 18 bytes , now at 22
Read in 4 bytes for filesize - now at 26
Filesize=79152
Read in two bytes namesize - now at 28
Namesize=9
Still at 28 skipping 2 bytes
skpped 2 bytes Now at filename 30
filename read in 9 bytes , Now at 39
adjusted filename should still be at 39
Filename=alert.ogg
skipping ahead 79152 bytes
Skiped File! Now at 79191
Got Header
Read in 4 bytes After header, now at 79195
Skipped ahead 18 bytes , now at 79213
Read in 4 bytes for filesize - now at 79217
Filesize=275
Read in two bytes namesize - now at 79219
Namesize=9
Still at 79219 skipping 2 bytes
skpped 2 bytes Now at filename 79221
filename read in 9 bytes , Now at 79230
adjusted filename should still be at 79230
Filename=arrow.png
skipping ahead 275 bytes
Skiped File! Now at 79505
Got Header
Read in 4 bytes After header, now at 79509
Skipped ahead 18 bytes , now at 79527
Read in 4 bytes for filesize - now at 79531
Filesize=12662
Read in two bytes namesize - now at 79533
Namesize=8
Still at 79533 skipping 2 bytes
skpped 2 bytes Now at filename 79535
filename read in 8 bytes , Now at 79543
adjusted filename should still be at 79543
Filename=beam.ogg
skipping ahead 12662 bytes
Skiped File! Now at 92205
Got Header
Read in 4 bytes After header, now at 92209
Skipped ahead 18 bytes , now at 92227
Read in 4 bytes for filesize - now at 92232
Filesize=707366
Read in two bytes namesize - now at 92234
Namesize=15
Still at 92234 skipping 2 bytes
skpped 2 bytes Now at filename 92236
filename read in 15 bytes , Now at 92251
adjusted filename should still be at 92251
Filename=border_back.png
skipping ahead 707366 bytes
Skiped File! Now at 799617
NO HEADER!

Pay close attention to the first and last reads..

Quote:

------
First read
------
Got Header
Read in 4 bytes After header, now at 4 (+4)
Skipped ahead 18 bytes , now at 22 (+18)
Read in 4 bytes for filesize - now at 26 (+4)
Filesize=79152
Read in two bytes namesize - now at 28 (+4)
Namesize=9
Still at 28 skipping 2 bytes
skpped 2 bytes Now at filename 30 (+2)
filename read in 9 bytes , Now at 39 (+9)
adjusted filename should still be at 39
Filename=alert.ogg
skipping ahead 79152 bytes
Skiped File! Now at 79191 (+79152)

------
Last read before failure:
------
Skiped File! Now at 92205
Got Header
Read in 4 bytes After header, now at 92209 (+4)
Skipped ahead 18 bytes , now at 92227 (+18)
Read in 4 bytes for filesize - now at 92232 (+5!!!! <------- IT IS NOW REPORTING +1 AHEAD OF THE SEEK POINTER!)
Filesize=707366 (This is correct!?)
Read in two bytes namesize - now at 92234 (wrong location!)
Namesize=15 (Still read in correct data, al_ftell(); is reporting +1 of where the seek pointer actually is)
Still at 92234 skipping 2 bytes
skpped 2 bytes Now at filename 92236
filename read in 15 bytes , Now at 92251
adjusted filename should still be at 92251
Filename=border_back.png (all of these are being read in properly even though al_ftell(); is still +1 bytes ahead of the actual seek pointer.
skipping ahead 707366 bytes
Skiped File! Now at 799617 (seek pointer and al_ftell() pointer now match, but now is off by +1 byte and is unable to read the header)
NO HEADER!

It seems to be screwing up doing a read after an al_fseek()

Here is my example code. To test yourself, use a zip file named default.zip with a few uncompressed files inside.

==EDIT==
I Attached an example zip file. This one is even more wacky because if you al_fseek() after the header read it reports that it's -29 bytes into the file

Windows 10 x64 BTW

#SelectExpand
  1#include 
  2#include 
  3#include 
  4#include 
  5#include 
  6#include 
  7#include 
  8
  9ALLEGRO_DISPLAY *d;
 10ALLEGRO_FILE *zip;
 11ALLEGRO_FILE *target;
 12
 13
 14void startup()
 15{
 16  if (!al_init()) {
 17    fprintf(stderr, "failed to initialize allegro!\n");
 18    exit(1);
 19  }
 20  if (!al_install_keyboard()) {
 21    fprintf(stderr, "Error installing keyboard.\n");
 22    exit(1);
 23  }
 24
 25  if (!al_init_primitives_addon()) {
 26    fprintf(stderr, "Error installing prims.\n");
 27    exit(1);
 28  }
 29
 30  if (!al_init_image_addon()) {
 31    fprintf(stderr, "Error installing image addon.\n");
 32    exit(1);
 33  }
 34
 35
 36  if (!al_init_font_addon()) {
 37    fprintf(stderr, "Error installing font addon.\n");
 38    exit(1);
 39  }
 40
 41  if (!al_init_ttf_addon()) {
 42    fprintf(stderr, "Error installing TTF addon.\n");
 43    exit(1);
 44  }
 45
 46
 47  d = al_create_display(1024, 768);
 48  al_clear_to_color(al_map_rgb(0, 0, 0));
 49
 50
 51}
 52
 53
 54int main(int argc, char **argv)
 55{
 56  int header;
 57  int filesize;
 58  int namesize;
 59  char filename[255];
 60
 61
 62  startup();
 63  zip=al_fopen("default.zip", "r");
 64  while (!al_feof(zip)) {
 65
 66
 67    header = al_fread32le(zip);
 68    if (header == 0x04034b50) { printf("Got Header\n"); }
 69    else { printf("NO HEADER!\n"); exit(1); }
 70    printf("Read in 4 bytes After header, now at %d\n", al_ftell(zip));
 71    al_fseek(zip, 18, ALLEGRO_SEEK_CUR);
 72    printf("Skipped ahead 18 bytes , now at %d\n", al_ftell(zip));
 73    filesize = al_fread32le(zip);
 74    printf("Read in 4 bytes for filesize - now at %d\n", al_ftell(zip));
 75    printf("Filesize=%d\n", filesize);
 76    namesize = al_fread16le(zip);
 77    printf("Read in two bytes namesize - now at %d\n", al_ftell(zip));
 78    printf("Namesize=%d\n", namesize);
 79    printf("Still at %d skipping 2 bytes\n", al_ftell(zip));
 80    al_fread16le(zip); //skip 2
 81    printf("skpped 2 bytes Now at filename %d\n", al_ftell(zip));
 82    al_fread(zip, filename, namesize);
 83    printf("filename read in %d bytes , Now at %d\n",namesize,  al_ftell(zip));
 84    filename[namesize] = '\0';
 85    printf("adjusted filename should still be at %d\n", al_ftell(zip));
 86    printf("Filename=%s\n", filename);
 87    printf("skipping ahead %d bytes\n", filesize);
 88    al_fseek(zip, filesize, ALLEGRO_SEEK_CUR);
 89    printf("Skipped File! Now at %d\n", al_ftell(zip));
 90  }
 91
 92
 93  while (1);

no-reply@allegro.cc (nshade) — Mon, 19 Nov 2018 01:35:34 +0000

HEADDESK

Man, Windows! Why do you make me want to hurt you?

no-reply@allegro.cc (Audric) — Mon, 19 Nov 2018 14:32:59 +0000

Actually it's libc's choice that unless you open files with "b" flag, the mode is "text" (And MS-DOS choice of line ending)

no-reply@allegro.cc (Edgar Reynaldo) — Mon, 19 Nov 2018 23:31:42 +0000

That's pretty much the first thing you learn when doing io. Binary or text mode.

Bug in allegro filestytem? I think that reads are drifting!