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rockbox/firmware/common/pathfuncs.c
Michael Sevakis e5042fd090 Add some comments about the behavior of a couple path functions. 
Critical reminders about the reasons path_dirname() and
path_basename() do certain things with a given kind of input and
how to interpret them.

Change-Id: I4e6ad29476bdd30abfb644f9360cc7dfd86298df
2017-02-07 02:45:26 -05:00

410 lines
12 KiB
C
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2014 by Michael Sevakis
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include <string.h>
#include <ctype.h>
#include "system.h"
#include "pathfuncs.h"
#include "string-extra.h"
#ifdef HAVE_MULTIVOLUME
#include <stdio.h>
#include "storage.h"
enum storage_name_dec_indexes
{
#if (CONFIG_STORAGE & STORAGE_ATA)
STORAGE_DEC_IDX_ATA,
#endif
#if (CONFIG_STORAGE & STORAGE_MMC)
STORAGE_DEC_IDX_MMC,
#endif
#if (CONFIG_STORAGE & STORAGE_SD)
STORAGE_DEC_IDX_SD,
#endif
#if (CONFIG_STORAGE & STORAGE_NAND)
STORAGE_DEC_IDX_NAND,
#endif
#if (CONFIG_STORAGE & STORAGE_RAMDISK)
STORAGE_DEC_IDX_RAMDISK,
#endif
#if (CONFIG_STORAGE & STORAGE_HOSTFS)
STORAGE_DEC_IDX_HOSTFS,
#endif
STORAGE_NUM_DEC_IDX,
};
static const char * const storage_dec_names[STORAGE_NUM_DEC_IDX+1] =
{
#if (CONFIG_STORAGE & STORAGE_ATA)
[STORAGE_DEC_IDX_ATA] = ATA_VOL_DEC,
#endif
#if (CONFIG_STORAGE & STORAGE_MMC)
[STORAGE_DEC_IDX_MMC] = MMC_VOL_DEC,
#endif
#if (CONFIG_STORAGE & STORAGE_SD)
[STORAGE_DEC_IDX_SD] = SD_VOL_DEC,
#endif
#if (CONFIG_STORAGE & STORAGE_NAND)
[STORAGE_DEC_IDX_NAND] = NAND_VOL_DEC,
#endif
#if (CONFIG_STORAGE & STORAGE_RAMDISK)
[STORAGE_DEC_IDX_RAMDISK] = RAMDISK_VOL_DEC,
#endif
#if (CONFIG_STORAGE & STORAGE_HOSTFS)
[STORAGE_DEC_IDX_HOSTFS] = HOSTFS_VOL_DEC,
#endif
[STORAGE_NUM_DEC_IDX] = DEFAULT_VOL_DEC,
};
static const unsigned char storage_dec_indexes[STORAGE_NUM_TYPES+1] =
{
[0 ... STORAGE_NUM_TYPES] = STORAGE_NUM_DEC_IDX,
#if (CONFIG_STORAGE & STORAGE_ATA)
[STORAGE_ATA_NUM] = STORAGE_DEC_IDX_ATA,
#endif
#if (CONFIG_STORAGE & STORAGE_MMC)
[STORAGE_MMC_NUM] = STORAGE_DEC_IDX_MMC,
#endif
#if (CONFIG_STORAGE & STORAGE_SD)
[STORAGE_SD_NUM] = STORAGE_DEC_IDX_SD,
#endif
#if (CONFIG_STORAGE & STORAGE_NAND)
[STORAGE_NAND_NUM] = STORAGE_DEC_IDX_NAND,
#endif
#if (CONFIG_STORAGE & STORAGE_RAMDISK)
[STORAGE_RAMDISK_NUM] = STORAGE_DEC_IDX_RAMDISK,
#endif
#if (CONFIG_STORAGE & STORAGE_HOSTFS)
[STORAGE_HOSTFS_NUM] = STORAGE_DEC_IDX_HOSTFS,
#endif
};
/* Returns on which volume this is and sets *nameptr to the portion of the
* path after the volume specifier, which could be the null if the path is
* just a volume root. If *nameptr > name, then a volume specifier was
* found. If 'greedy' is 'true', then it all separators after the volume
* specifier are consumed, if one was found.
*/
int path_strip_volume(const char *name, const char **nameptr, bool greedy)
{
int volume = 0;
const char *t = name;
int c, v = 0;
/* format: "/<xxx##>/foo/bar"
* the "xxx" is pure decoration; only an unbroken trailing string of
* digits within the brackets is parsed as the volume number and of
* those, only the last ones VOL_MUM_MAX allows.
*/
c = *(t = GOBBLE_PATH_SEPCH(t)); /* skip all leading slashes */
if (c != VOL_START_TOK) /* missing start token? no volume */
goto volume0;
do
{
switch (c)
{
case '0' ... '9': /* digit; parse volume number */
v = (v * 10 + c - '0') % VOL_NUM_MAX;
break;
case '\0':
case PATH_SEPCH: /* no closing bracket; no volume */
goto volume0;
default: /* something else; reset volume */
v = 0;
}
}
while ((c = *++t) != VOL_END_TOK); /* found end token? */
if (!(c = *++t)) /* no more path and no '/' is ok */
;
else if (c != PATH_SEPCH) /* more path and no separator after end */
goto volume0;
else if (greedy)
t = GOBBLE_PATH_SEPCH(++t); /* strip remaining separators */
/* if 'greedy' is true and **nameptr == '\0' then it's only a volume
root whether or not it has trailing separators */
volume = v;
name = t;
volume0:
if (nameptr)
*nameptr = name;
return volume;
}
/* Returns the volume specifier decorated with the storage type name.
* Assumes the supplied buffer size is at least {VOL_MAX_LEN}+1.
*/
int get_volume_name(int volume, char *buffer)
{
if (volume < 0)
{
*buffer = '\0';
return 0;
}
volume %= VOL_NUM_MAX; /* as path parser would have it */
int type = storage_driver_type(volume_drive(volume));
if (type < 0 || type > STORAGE_NUM_TYPES)
type = STORAGE_NUM_TYPES;
const char *voldec = storage_dec_names[storage_dec_indexes[type]];
return snprintf(buffer, VOL_MAX_LEN + 1, "%c%s%d%c",
VOL_START_TOK, voldec, volume, VOL_END_TOK);
}
#endif /* HAVE_MULTIVOLUME */
/* Just like path_strip_volume() but strips a leading drive specifier and
* returns the drive number (A=0, B=1, etc.). -1 means no drive was found.
* If 'greedy' is 'true', all separators after the volume are consumed.
*/
int path_strip_drive(const char *name, const char **nameptr, bool greedy)
{
int c = toupper(*name);
if (c >= 'A' && c <= 'Z' && name[1] == PATH_DRVSEPCH)
{
name = &name[2];
if (greedy)
name = GOBBLE_PATH_SEPCH(name);
*nameptr = name;
return c - 'A';
}
*nameptr = name;
return -1;
}
/* Strips directory components from the path
* "" *nameptr->NUL, len=0: ""
* "/" *nameptr->/, len=1: "/"
* "//" *nameptr->2nd /, len=1: "/"
* "/a" *nameptr->a, len=1: "a"
* "a/" *nameptr->a, len=1: "a"
* "/a/bc" *nameptr->b, len=2: "bc"
* "d" *nameptr->d, len=1: "d"
* "ef/gh" *nameptr->g, len=2: "gh"
*
* Notes: * Doesn't do suffix removal at this time.
* * In the same string, path_dirname() returns a pointer with the
* same or lower address as path_basename().
* * Pasting a separator between the returns of path_dirname() and
* path_basename() will result in a path equivalent to the input.
*/
size_t path_basename(const char *name, const char **nameptr)
{
const char *p = name;
const char *q = p;
const char *r = q;
while (*(p = GOBBLE_PATH_SEPCH(p)))
{
q = p;
p = GOBBLE_PATH_COMP(++p);
r = p;
}
if (r == name && p > name)
q = p, r = q--; /* root - return last slash */
/* else path is an empty string */
*nameptr = q;
return r - q;
}
/* Strips the trailing component from the path
* "" *nameptr->NUL, len=0: ""
* "/" *nameptr->/, len=1: "/"
* "//" *nameptr->2nd /, len=1: "/"
* "/a" *nameptr->/, len=1: "/"
* "a/" *nameptr->a, len=0: ""
* "/a/bc" *nameptr->/, len=2: "/a"
* "d" *nameptr->d, len=0: ""
* "ef/gh" *nameptr->e, len=2: "ef"
*
* Notes: * Interpret len=0 as ".".
* * In the same string, path_dirname() returns a pointer with the
* same or lower address as path_basename().
* * Pasting a separator between the returns of path_dirname() and
* path_basename() will result in a path equivalent to the input.
*
*/
size_t path_dirname(const char *name, const char **nameptr)
{
const char *p = GOBBLE_PATH_SEPCH(name);
const char *q = name;
const char *r = p;
while (*(p = GOBBLE_PATH_COMP(p)))
{
const char *s = p;
if (!*(p = GOBBLE_PATH_SEPCH(p)))
break;
q = s;
}
if (q == name && r > name)
name = r, q = name--; /* root - return last slash */
*nameptr = name;
return q - name;
}
/* Removes trailing separators from a path
* "" *nameptr->NUL, len=0: ""
* "/" *nameptr->/, len=1: "/"
* "//" *nameptr->2nd /, len=1: "/"
* "/a/" *nameptr->/, len=2: "/a"
* "//b/" *nameptr->1st /, len=3: "//b"
* "/c/" *nameptr->/, len=2: "/c"
*/
size_t path_strip_trailing_separators(const char *name, const char **nameptr)
{
const char *p;
size_t len = path_basename(name, &p);
if (len == 1 && *p == '/' && p > name)
{
*nameptr = p;
name = p - 1; /* root with multiple separators */
}
else
{
*nameptr = name;
p += len; /* length to end of basename */
}
return p - name;
}
/* Transforms "wrong" separators into the correct ones
* "c:\windows\system32" -> "c:/windows/system32"
*
* 'path' and 'dstpath' may either be the same buffer or non-overlapping
*/
void path_correct_separators(char *dstpath, const char *path)
{
char *dstp = dstpath;
const char *p = path;
while (1)
{
const char *next = strchr(p, PATH_BADSEPCH);
if (!next)
break;
size_t size = next - p;
if (dstpath != path)
memcpy(dstp, p, size); /* not in-place */
dstp += size;
*dstp++ = PATH_SEPCH;
p = next + 1;
}
if (dstpath != path)
strcpy(dstp, p);
}
/* Appends one path to another, adding separators between components if needed.
* Return value and behavior is otherwise as strlcpy so that truncation may be
* detected.
*
* For basepath and component:
* PA_SEP_HARD adds a separator even if the base path is empty
* PA_SEP_SOFT adds a separator only if the base path is not empty
*/
size_t path_append(char *buf, const char *basepath,
const char *component, size_t bufsize)
{
const char *base = basepath && basepath[0] ? basepath : buf;
if (!base)
return bufsize; /* won't work to get lengths from buf */
if (!buf)
bufsize = 0;
if (path_is_absolute(component))
{
/* 'component' is absolute; replace all */
basepath = component;
component = "";
}
/* if basepath is not null or empty, buffer contents are replaced,
otherwise buf contains the base path */
size_t len = base == buf ? strlen(buf) : strlcpy(buf, basepath, bufsize);
bool separate = false;
if (!basepath || !component)
separate = !len || base[len-1] != PATH_SEPCH;
else if (component[0])
separate = len && base[len-1] != PATH_SEPCH;
/* caller might lie about size of buf yet use buf as the base */
if (base == buf && bufsize && len >= bufsize)
buf[bufsize - 1] = '\0';
buf += len;
bufsize -= MIN(len, bufsize);
if (separate && (len++, bufsize > 0) && --bufsize > 0)
*buf++ = PATH_SEPCH;
return len + strlcpy(buf, component ?: "", bufsize);
}
/* Returns the location and length of the next path component, consuming the
* input in the process.
*
* "/a/bc/d" breaks into:
* start: *namep->1st /
* call 1: *namep->a, *pathp->2nd / len=1: "a"
* call 2: *namep->b, *pathp->3rd / len=2: "bc"
* call 3: *namep->d, *pathp->NUL, len=1: "d"
* call 4: *namep->NUL, *pathp->NUL, len=0: ""
*
* Returns: 0 if the input has been consumed
* The length of the component otherwise
*/
ssize_t parse_path_component(const char **pathp, const char **namep)
{
/* a component starts at a non-separator and continues until the next
separator or null */
const char *p = GOBBLE_PATH_SEPCH(*pathp);
const char *name = p;
if (*p)
p = GOBBLE_PATH_COMP(++p);
*pathp = p;
*namep = name;
return p - name;
}
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