/*.......................................................................
* Append a string to a pathname, increasing the size of the pathname
* buffer if needed.
*
* Input:
* path PathName * The pathname container.
* string const char * The string to be appended to the pathname.
* Note that regardless of the slen argument,
* this should be a '\0' terminated string.
* slen int The maximum number of characters to append
* from string[], or -1 to append the whole
* string.
* remove_escapes int If true, remove the backslashes that escape
* spaces, tabs, backslashes etc..
* Output:
* return char * The pathname string path->name[], which may
* have been reallocated, or NULL if there was
* insufficient memory to extend the pathname.
*/
char *_pn_append_to_path(PathName *path, const char *string, int slen,
int remove_escapes)
{
int pathlen; /* The length of the pathname */
int i;
/*
* Check the arguments.
*/
if(!path || !string) {
errno = EINVAL;
return NULL;
};
/*
* Get the current length of the pathname.
*/
pathlen = strlen(path->name);
/*
* How many characters should be appended?
*/
if(slen < 0 || slen > strlen(string))
slen = strlen(string);
/*
* Resize the pathname if needed.
*/
if(!_pn_resize_path(path, pathlen + slen))
return NULL;
/*
* Append the string to the output pathname, removing any escape
* characters found therein.
*/
if(remove_escapes) {
int is_escape = 0;
for(i=0; i<slen; i++) {
is_escape = !is_escape && string[i] == '\\';
if(!is_escape)
path->name[pathlen++] = string[i];
};
/*
* Terminate the string.
*/
path->name[pathlen] = '\0';
} else {
/*
* Append the string directly to the pathname.
*/
memcpy(path->name + pathlen, string, slen);
path->name[pathlen + slen] = '\0';
};
return path->name;
}
/*.......................................................................
* Preprocess a path, expanding ~/, ~user/ and $envvar references, using
* ef->path as a work buffer, then copy the result into a cache entry,
* and return a pointer to this copy.
*
* Input:
* ef ExpandFile * The resource object of the file matcher.
* pathlen int The length of the prefix of path[] to be expanded.
* Output:
* return char * A pointer to a copy of the output path in the
* cache. On error NULL is returned, and a description
* of the error is left in ef->errmsg[].
*/
static char *ef_expand_special(ExpandFile *ef, const char *path, int pathlen)
{
int spos; /* The index of the start of the path segment that needs */
/* to be copied from path[] to the output pathname. */
int ppos; /* The index of a character in path[] */
char *pptr; /* A pointer into the output path */
int escaped; /* True if the previous character was a '\' */
int i;
/*
* Clear the pathname buffer.
*/
_pn_clear_path(ef->path);
/*
* We need to perform two passes, one to expand environment variables
* and a second to do tilde expansion. This caters for the case
* where an initial dollar expansion yields a tilde expression.
*/
escaped = 0;
for(spos=ppos=0; ppos < pathlen; ppos++) {
int c = path[ppos];
if(escaped) {
escaped = 0;
} else if(c == '\\') {
escaped = 1;
} else if(c == '$') {
int envlen; /* The length of the environment variable */
char *value; /* The value of the environment variable */
/*
* Record the preceding unrecorded part of the pathname.
*/
if(spos < ppos && _pn_append_to_path(ef->path, path + spos, ppos-spos, 0)
== NULL) {
strncpy(ef->errmsg, "Insufficient memory to expand path", sizeof(ef->errmsg));
return NULL;
};
/*
* Skip the dollar.
*/
ppos++;
/*
* Copy the environment variable name that follows the dollar into
* ef->envnam[], stopping if a directory separator or end of string
* is seen.
*/
for(envlen=0; envlen<ENV_LEN && ppos < pathlen &&
strncmp(path + ppos, FS_DIR_SEP, FS_DIR_SEP_LEN); envlen++)
ef->envnam[envlen] = path[ppos++];
/*
* If the username overflowed the buffer, treat it as invalid (note that
* on most unix systems only 8 characters are allowed in a username,
* whereas our ENV_LEN is much bigger than that.
*/
if(envlen >= ENV_LEN) {
strncpy(ef->errmsg, "Environment variable name too long", sizeof(ef->errmsg));
return NULL;
};
/*
* Terminate the environment variable name.
*/
ef->envnam[envlen] = '\0';
/*
* Lookup the value of the environment variable.
*/
value = getenv(ef->envnam);
if(!value) {
const char *fmt = "No expansion found for: $%.*s";
snprintf(ef->errmsg, sizeof(ef->errmsg), fmt, ERRLEN - strlen(fmt),
ef->envnam);
return NULL;
};
/*
* Copy the value of the environment variable into the output pathname.
*/
if(_pn_append_to_path(ef->path, value, -1, 0) == NULL) {
strncpy(ef->errmsg, "Insufficient memory to expand path", sizeof(ef->errmsg));
return NULL;
};
/*
* Record the start of the uncopied tail of the input pathname.
*/
spos = ppos;
};
};
/*
* Record the uncopied tail of the pathname.
*/
if(spos < ppos && _pn_append_to_path(ef->path, path + spos, ppos-spos, 0)
== NULL) {
strncpy(ef->errmsg, "Insufficient memory to expand path", sizeof(ef->errmsg));
return NULL;
};
/*
* If the first character of the resulting pathname is a tilde,
* then attempt to substitute the home directory of the specified user.
*/
pptr = ef->path->name;
if(*pptr == '~' && path[0] != '\\') {
int usrlen; /* The length of the username following the tilde */
const char *homedir; /* The home directory of the user */
int homelen; /* The length of the home directory string */
int plen; /* The current length of the path */
int skip=0; /* The number of characters to skip after the ~user */
/*
* Get the current length of the output path.
*/
plen = strlen(ef->path->name);
/*
* Skip the tilde.
*/
pptr++;
/*
* Copy the optional username that follows the tilde into ef->usrnam[].
*/
for(usrlen=0; usrlen<USR_LEN && *pptr &&
strncmp(pptr, FS_DIR_SEP, FS_DIR_SEP_LEN); usrlen++)
ef->usrnam[usrlen] = *pptr++;
/*
* If the username overflowed the buffer, treat it as invalid (note that
* on most unix systems only 8 characters are allowed in a username,
* whereas our USR_LEN is much bigger than that.
*/
if(usrlen >= USR_LEN) {
strncpy(ef->errmsg, "Username too long", sizeof(ef->errmsg));
return NULL;
};
/*
* Terminate the username string.
*/
ef->usrnam[usrlen] = '\0';
/*
* Lookup the home directory of the user.
*/
homedir = _hd_lookup_home_dir(ef->home, ef->usrnam);
if(!homedir) {
strncpy(ef->errmsg, _hd_last_home_dir_error(ef->home), ERRLEN);
ef->errmsg[ERRLEN] = '\0';
return NULL;
};
homelen = strlen(homedir);
/*
* ~user and ~ are usually followed by a directory separator to
* separate them from the file contained in the home directory.
* If the home directory is the root directory, then we don't want
* to follow the home directory by a directory separator, so we must
* erase it.
*/
if(strcmp(homedir, FS_ROOT_DIR) == 0 &&
strncmp(pptr, FS_DIR_SEP, FS_DIR_SEP_LEN) == 0) {
skip = FS_DIR_SEP_LEN;
};
/*
* If needed, increase the size of the pathname buffer to allow it
* to accomodate the home directory instead of the tilde expression.
* Note that pptr may not be valid after this call.
*/
if(_pn_resize_path(ef->path, plen - usrlen - 1 - skip + homelen)==NULL) {
strncpy(ef->errmsg, "Insufficient memory to expand filename", sizeof(ef->errmsg));
return NULL;
};
/*
* Move the part of the pathname that follows the tilde expression to
* the end of where the home directory will need to be inserted.
*/
memmove(ef->path->name + homelen,
ef->path->name + 1 + usrlen + skip, plen - usrlen - 1 - skip+1);
/*
* Write the home directory at the beginning of the string.
*/
for(i=0; i<homelen; i++)
ef->path->name[i] = homedir[i];
};
/*
* Copy the result into the cache, and return a pointer to the copy.
*/
return ef_cache_pathname(ef, ef->path->name, 0);
}
/*.......................................................................
* Prepend a string to a pathname, increasing the size of the pathname
* buffer if needed.
*
* Input:
* path PathName * The pathname container.
* string const char * The string to be prepended to the pathname.
* Note that regardless of the slen argument,
* this should be a '\0' terminated string.
* slen int The maximum number of characters to prepend
* from string[], or -1 to append the whole
* string.
* remove_escapes int If true, remove the backslashes that escape
* spaces, tabs, backslashes etc..
* Output:
* return char * The pathname string path->name[], which may
* have been reallocated, or NULL if there was
* insufficient memory to extend the pathname.
*/
char *_pn_prepend_to_path(PathName *path, const char *string, int slen,
int remove_escapes)
{
int pathlen; /* The length of the pathname */
int shift; /* The number of characters to shift the suffix by */
int i,j;
/*
* Check the arguments.
*/
if(!path || !string) {
errno = EINVAL;
return NULL;
};
/*
* Get the current length of the pathname.
*/
pathlen = strlen(path->name);
/*
* How many characters should be appended?
*/
if(slen < 0 || slen > strlen(string))
slen = strlen(string);
/*
* Work out how far we need to shift the original path string to make
* way for the new prefix. When removing escape characters, we need
* final length of the new prefix, after unescaped backslashes have
* been removed.
*/
if(remove_escapes) {
int is_escape = 0;
for(shift=0,i=0; i<slen; i++) {
is_escape = !is_escape && string[i] == '\\';
if(!is_escape)
shift++;
};
} else {
shift = slen;
};
/*
* Resize the pathname if needed.
*/
if(!_pn_resize_path(path, pathlen + shift))
return NULL;
/*
* Make room for the prefix at the beginning of the string.
*/
memmove(path->name + shift, path->name, pathlen+1);
/*
* Copy the new prefix into the vacated space at the beginning of the
* output pathname, removing any escape characters if needed.
*/
if(remove_escapes) {
int is_escape = 0;
for(i=j=0; i<slen; i++) {
is_escape = !is_escape && string[i] == '\\';
if(!is_escape)
path->name[j++] = string[i];
};
} else {
memcpy(path->name, string, slen);
};
return path->name;
}