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Fix two string output functions' handling of their buffer-size parameter.

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That parameter's type is unsigned; but, the functions return an int.  If the size is too big for a signed integer, then return an error code.
If the size is zero, then don't write anything into a buffer (the buffer pointer may be NULL).  But, do format and count the arguments.
This commit is contained in:
Greg King 2015-07-09 10:28:38 -04:00
parent 74074a20b2
commit 219905c6bc
1 changed files with 25 additions and 22 deletions
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47
libsrc/common/vsnprintf.s
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@ -1,7 +1,8 @@
;
; int __fastcall__ vsnprintf (char* Buf, size_t size, const char* Format, va_list ap);
;
; Ullrich von Bassewitz, 2009-09-26
; 2009-09-26, Ullrich von Bassewitz
; 2015-07-09, Greg King
;
.export _vsnprintf, vsnprintf
@ -9,6 +10,8 @@
.import _memcpy, __printf
.importzp sp, ptr1
.include "errno.inc"
.macpack generic
.data
@ -46,8 +49,10 @@ vsnprintf:
sta ccount+1 ; Clear ccount
; Get the size parameter and replace it by a pointer to outdesc. This is to
; build a stack frame for the call to _printf.
; If size is zero, there's nothing to do.
; build a stack frame for the call to _printf. The size must not be greater
; than INT_MAX because the return type is int. If the size is zero,
; then nothing will be written into the buffer; but, the arguments still will
; be formatted and counted.
ldy #2
lda (sp),y
@ -58,15 +63,13 @@ vsnprintf:
iny
lda (sp),y
bmi L9 ; More than $7FFF
sta ptr1+1
ora ptr1
beq L9
lda #>outdesc
sta (sp),y
; Write size-1 to outdesc.uns
; Write size-1 to outdesc.uns. It will be -1 if there is no buffer.
ldy ptr1+1
ldx ptr1
@ -90,17 +93,18 @@ L1: dex
pla
jsr __printf
; Terminate the string. The last char is either at bufptr+ccount or
; bufptr+bufsize, whichever is smaller.
; Terminate the string if there is a buffer. The last char. is at either
; bufptr+bufsize or bufptr+ccount, whichever is smaller.
ldx bufsize+1
bmi L4 ; -1 -- No buffer
lda bufsize+0
cpx ccount+1
bne L2
cmp ccount+0
L2: bcc L3
lda ccount+0
ldx ccount+1
cpx bufsize+1
bne L2
cmp bufsize+0
L2: bcc L3
lda bufsize+0
ldx bufsize+1
clc
L3: adc bufptr+0
sta ptr1
@ -114,16 +118,14 @@ L3: adc bufptr+0
; Return the number of bytes written and drop buf
lda ccount+0
L4: lda ccount+0
ldx ccount+1
jmp incsp2
; Bail out if size is zero.
; Bail out if size is too high.
L9: pla
pla ; Discard ap
lda #0
tax
L9: lda #ERANGE
jsr __directerrno ; Return -1
jmp incsp6 ; Drop parameters
@ -146,10 +148,11 @@ out:
sbc ccount+0 ; Low byte of bytes already written
sta ptr1
lda bufsize+1
bmi @L9 ; -1 -- No buffer
sbc ccount+1
sta ptr1+1
bcs @L0 ; Branch if space left
lda #$00
@L9: lda #$0000
sta ptr1
sta ptr1+1 ; No space left