The commit d6c0e1e2ffbf7913ab69d51cc794d48d41c8fcb1 ("[BUILTIN]
Handle embedded NULs correctly in printf") caused a performance
regression in the echo built-in because every echo call now goes
through the printf %b slow path where the string is always printed
twice to ensure the space padding is correct in the presence of
NUL characters. In fact this regression applies to printf %b as
well.
This is easily fixed by making printf %b take the fast path when
no precision/field width modifiers are present.
This patch also changes the second strchurnul call to strspn which
generates slightly better code.
Signed-off-by: Herbert Xu <[email protected]>
diff --git a/src/bltin/printf.c b/src/bltin/printf.c
index ec7c8c2..eaf14b6 100644
--- a/src/bltin/printf.c
+++ b/src/bltin/printf.c
@@ -98,20 +98,25 @@ static int print_escape_str(const char *f, int *param, int
*array, char *s)
int total;
setstackmark(&smark);
- done = conv_escape_str(s, &p);
- q = stackblock();
- len = p - q;
+ done = conv_escape_str(s, &q);
+ p = stackblock();
+ len = q - p;
+ total = len - 1;
+
+ if (f[1] == 's')
+ goto easy;
- p = makestrspace(len, p);
- memset(p, 'X', len - 1);
- p[len - 1] = 0;
+ p = makestrspace(len, q);
+ memset(p, 'X', total);
+ p[total] = 0;
q = stackblock();
total = ASPF(&p, f, p);
len = strchrnul(p, 'X') - p;
- memcpy(p + len, q, strchrnul(p + len, ' ') - (p + len));
+ memcpy(p + len, q, strspn(p + len, "X"));
+easy:
out1mem(p, total);
popstackmark(&smark);
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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