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New function _dirskip that allows to skip an amount of bytes from the

directory with error check.


git-svn-id: svn://svn.cc65.org/cc65/trunk@5668 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2012-06-01 19:23:34 +00:00
parent 8087959e18
commit eab5f250ad
5 changed files with 117 additions and 10 deletions

View File

@ -65,6 +65,7 @@ S_OBJS = c_acptr.o \
closedir.o \
ctype.o \
cvline.o \
dir.o \
diskcmd.o \
exehdr.o \
filedes.o \

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@ -24,6 +24,22 @@ struct DIR {
/*****************************************************************************/
/* Code */
/*****************************************************************************/
unsigned char __fastcall__ _dirskip (unsigned char count, struct DIR* dir);
/* Skip bytes from the directory and make sure, errno is set if this isn't
* possible. Return true if anything is ok and false otherwise. For
* simplicity we assume that read will never return less than count if there
* is no error and end-of-file is not reached.
* Note: count must not be more than 254.
*/
/* End of dir.h */
#endif

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@ -23,5 +23,5 @@
.global _readdir
.global _telldir
.global _rewinddir
.global __dirskip

92
libsrc/cbm/dir.s Normal file
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@ -0,0 +1,92 @@
;
; Ullrich von Bassewitz, 2012-06-01
;
; unsigned char __fastcall__ _dirskip (unsigned char count, struct DIR* dir);
; /* Skip bytes from the directory and make sure, errno is set if this isn't
; * possible. Return true if anything is ok and false otherwise. For
; * simplicity we assume that read will never return less than count if there
; * is no error and end-of-file is not reached.
; * Note: count must not be more than 254.
; */
;
.include "dir.inc"
.include "errno.inc"
.include "zeropage.inc"
.import _read
.import pushax, pushptr1idx
.import subysp, addysp1
.proc __dirskip
sta ptr1
stx ptr1+1 ; Save dir
; Get count and allocate space on the stack
ldy #0
lda (sp),y
pha
tay
jsr subysp
; Save current value of sp
lda sp
pha
lda sp+1
pha
; Push dir->fd
ldy #DIR::fd+1
jsr pushptr1idx
; Push pointer to buffer
pla
tax
pla
jsr pushax
; Load count and call read
pla
pha
ldx #0
jsr _read
; Check for errors. In case of errors, errno is already set.
cpx #$FF
bne L2
; read() returned an error
pla ; Count
tay
lda #0
tax
L1: jmp addysp1 ; Drop buffer plus count
; read() was successful, check number of bytes read. We assume that read will
; not return more than count, so X is zero if we come here.
L2: sta tmp1
pla ; count
tay
cmp tmp1
beq L1 ; Drop variables, return count
; Didn't read enough bytes. This is an error for us, but errno is not set
lda #<EIO
sta __errno
stx __errno+1
txa ; A=X=0
beq L1 ; Branch always
.endproc

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@ -1,3 +1,7 @@
/*
* Ullrich von Bassewitz, 2012-05-30. Based on code by Groepaz.
*/
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
@ -10,10 +14,8 @@
DIR* __fastcall__ opendir (const char*)
{
unsigned char buffer[8+16+1+7];
int count;
DIR d;
DIR* dir = 0;
DIR d;
/* Setup file name and offset */
d.name[0] = '$';
@ -25,8 +27,7 @@ DIR* __fastcall__ opendir (const char*)
if (d.fd >= 0) {
/* Skip the disk header */
count = read (d.fd, buffer, sizeof (buffer));
if (count == sizeof (buffer)) {
if (_dirskip (32, &d)) {
/* Allocate memory for the DIR structure returned */
dir = malloc (sizeof (*dir));
@ -38,9 +39,6 @@ DIR* __fastcall__ opendir (const char*)
/* Set an appropriate error code */
errno = ENOMEM;
}
} else if (count >= 0) {
/* Short read - need to set an error code */
errno = EIO;
}
}