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103 lines
2.3 KiB
C
103 lines
2.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) many different people.
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* If you wrote this, please acknowledge your work.
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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/* Concatenate path and filename to new allocated buffer.
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* Add '/' only as needed (no duplicate // are produced).
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* If path is NULL, it is assumed to be "/".
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* filename should not be NULL.
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*/
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char* FAST_FUNC concat_path_file(const char *path, const char *filename)
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{
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#if 0
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char *lc;
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if (!path)
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path = "";
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lc = last_char_is(path, '/');
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while (*filename == '/')
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filename++;
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return xasprintf("%s%s%s", path, (lc==NULL ? "/" : ""), filename);
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#else
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/* ^^^^^^^^^^^ timing of xasprintf-based code above:
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* real 7.074s
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* user 0.156s <<<
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* sys 6.394s
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* "rm -rf" of a Linux kernel tree from tmpfs (run time still dominated by in-kernel work, though)
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* real 6.989s
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* user 0.055s <<< 3 times less CPU used
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* sys 6.450s
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* vvvvvvvvvvv timing of open-coded malloc+memcpy code below (+59 bytes):
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*/
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char *buf, *p;
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size_t n1, n2, n3;
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while (*filename == '/')
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filename++;
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if (!path || !path[0])
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return xstrdup(filename);
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n1 = strlen(path);
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n2 = (path[n1 - 1] != '/'); /* 1: "path has no trailing slash" */
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n3 = strlen(filename) + 1;
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buf = xmalloc(n1 + n2 + n3);
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p = mempcpy(buf, path, n1);
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if (n2)
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*p++ = '/';
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memcpy(p, filename, n3);
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return buf;
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#endif
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}
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/* If second component comes from struct dirent,
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* it's possible to eliminate one strlen() by using name length
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* provided by kernel in struct dirent. See below.
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* However, the win seems to be insignificant.
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*/
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#if 0
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/* Extract d_namlen from struct dirent */
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static size_t get_d_namlen(const struct dirent *de)
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{
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#if defined(_DIRENT_HAVE_D_NAMLEN)
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return de->d_namlen;
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#elif defined(_DIRENT_HAVE_D_RECLEN)
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const size_t prefix_sz = offsetof(struct dirent, d_name);
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return de->d_reclen - prefix_sz;
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#else
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return strlen(de->d_name);
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#endif
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}
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char* FAST_FUNC concat_path_dirent(const char *path, const struct dirent *de)
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{
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char *buf, *p;
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size_t n1, n2, n3;
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if (!path || !path[0])
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return xstrdup(de->d_name);
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n1 = strlen(path);
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n2 = (path[n1 - 1] != '/');
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n3 = get_d_namlen(de) + 1;
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buf = xmalloc(n1 + n2 + n3);
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p = mempcpy(buf, path, n1);
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if (n2)
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*p++ = '/';
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memcpy(p, de->d_name, n3);
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return buf;
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}
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#endif
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