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Add unlink(2) implementation for CP/M. #235

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Add unlink(2) implementation for CP/M. #235

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39 changes: 39 additions & 0 deletions plat/cpm/libsys/unlink.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
#include <errno.h>
#include <unistd.h>
#include <cpm.h>
#include "cpmsys.h"

int unlink(const char* path)
{
uint8_t fd = 0;
struct FCBE* fcbe = &__fd[0];
uint8_t olduser;

__init_file_descriptors();
while (fd != NUM_FILE_DESCRIPTORS)
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It's been a while since I looked at this code, but I believe that this chunk is trying to find a free FCBE structure for use when parsing the filename, right? I think it would actually be more efficient to have a static structure used by unlink() instead --- the size of the structure is probably smaller than the size of the code needed to manage allocating one.

{
if (fcbe->fcb.f[0] == 0)
break;
fd++;
fcbe++;
}
if (fd == NUM_FILE_DESCRIPTORS)
{
errno = EMFILE;
return -1;
}

fcbe->user = cpm_parse_filename(&fcbe->fcb, path);

olduser = cpm_get_user();
cpm_set_user(fcbe->user);

if (cpm_delete_file(&fcbe->fcb) == 0xff)
{
fcbe->fcb.f[0] = 0;
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IIUIC, this will leak the FCBE if the call succeeds. (I assume you don't want to allocate one permanently, right?)

errno = EIO;
return -1;
}

return 0;
}