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0a9df786a6
This adds kvasprintf_const which tries to use kstrdup_const if possible: If the format string contains no % characters, or if the format string is exactly "%s", we delegate to kstrdup_const. Otherwise, we fall back to kvasprintf. Just as for kstrdup_const, the main motivation is to save memory by reusing .rodata when possible. The return value should be freed by kfree_const, just like for kstrdup_const. There is deliberately no kasprintf_const: In the vast majority of cases, the format string argument is a literal, so one can determine statically whether one could instead use kstrdup_const directly (which would also require one to change all corresponding kfree calls to kfree_const). Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
62 lines
1.2 KiB
C
62 lines
1.2 KiB
C
/*
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* linux/lib/kasprintf.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <stdarg.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/string.h>
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/* Simplified asprintf. */
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char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
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{
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unsigned int len;
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char *p;
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va_list aq;
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va_copy(aq, ap);
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len = vsnprintf(NULL, 0, fmt, aq);
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va_end(aq);
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p = kmalloc_track_caller(len+1, gfp);
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if (!p)
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return NULL;
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vsnprintf(p, len+1, fmt, ap);
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return p;
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}
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EXPORT_SYMBOL(kvasprintf);
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/*
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* If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt
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* (or the sole vararg) points to rodata, we will then save a memory
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* allocation and string copy. In any case, the return value should be
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* freed using kfree_const().
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*/
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const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap)
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{
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if (!strchr(fmt, '%'))
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return kstrdup_const(fmt, gfp);
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if (!strcmp(fmt, "%s"))
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return kstrdup_const(va_arg(ap, const char*), gfp);
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return kvasprintf(gfp, fmt, ap);
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}
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EXPORT_SYMBOL(kvasprintf_const);
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char *kasprintf(gfp_t gfp, const char *fmt, ...)
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{
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va_list ap;
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char *p;
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va_start(ap, fmt);
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p = kvasprintf(gfp, fmt, ap);
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va_end(ap);
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return p;
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}
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EXPORT_SYMBOL(kasprintf);
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