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common safe write(2) wrapper

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This commit is contained in:
dtb 2022-06-14 17:29:23 -04:00
parent a304049598
commit 12d2cef2d4
1 changed files with 15 additions and 7 deletions
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22
lib/libio.c
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@ -10,9 +10,22 @@ _strlen(char *s){
return i; return i;
} }
static int
_write(int fd, char *s, int n){
int i;
for(
i = 0;
i < n;
i += write(fd, s+i, n-i)
);
return i;
}
int int
fdprint(int fd, char *s){ fdprint(int fd, char *s){
write(fd, s, _strlen(s)); return _write(fd, s, _strlen(s));
} }
/* SLOW. DO NOT USE. */ /* SLOW. DO NOT USE. */
@ -45,7 +58,6 @@ fdputs(int fd, char *s){
int r; int r;
i = _strlen(s); i = _strlen(s);
r = 0;
/* RACE CONDITION */ /* RACE CONDITION */
/* This leaves s as an invalid string while the write(2) syscall is /* This leaves s as an invalid string while the write(2) syscall is
@ -53,11 +65,7 @@ fdputs(int fd, char *s){
* implementation is unsuitable when s is shared between threads or * implementation is unsuitable when s is shared between threads or
* whatever the CS term for that is. */ * whatever the CS term for that is. */
s[i] = '\n'; s[i] = '\n';
for( r = _write(fd, s, i + 1);
r = 0;
(r += write(fd, s, i + 1)) < i + 1;
s += r, i -= r
);
s[i] = '\0'; s[i] = '\0';
return r; return r;