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Rework copyinstr to:

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* Fail when the length passed in is 0
 * Remove an unneeded increment of the count on success
 * Return ENAMETOOLONG when the input pointer is too long

Sponsored by:	ABT Systems Ltd
This commit is contained in:
Andrew Turner 2015-09-09 11:51:14 +00:00
parent f9f9625d18
commit 8fe99e427f
1 changed files with 6 additions and 4 deletions
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10
sys/arm64/arm64/copyinout.S
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@ -95,6 +95,7 @@ END(copyin)
*/
ENTRY(copyinstr)
mov x5, xzr /* count = 0 */
mov w4, #1 /* If zero return faulure */
cbz x2, 3f /* If len == 0 then skip loop */
adr x6, copyio_fault /* Get the handler address */
@ -102,17 +103,18 @@ ENTRY(copyinstr)
1: ldrb w4, [x0], #1 /* Load from uaddr */
strb w4, [x1], #1 /* Store in kaddr */
cbz w4, 2f /* If == 0 then break */
sub x2, x2, #1 /* len-- */
add x5, x5, #1 /* count++ */
cbz w4, 2f /* Break when NUL-terminated */
sub x2, x2, #1 /* len-- */
cbnz x2, 1b
2: SET_FAULT_HANDLER(xzr, x7) /* Clear the handler */
3: cbz x3, 4f /* Check if done != NULL */
add x5, x5, #1 /* count++ */
str x5, [x3] /* done = count */
4: mov x0, xzr /* return 0 */
4: mov w1, #ENAMETOOLONG /* Load ENAMETOOLONG to return if failed */
cmp w4, #0 /* Check if we saved the NUL-terminator */
csel w0, wzr, w1, eq /* If so return success, else failure */
ret
END(copyinstr)