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Diffstat (limited to 'sntp/libopts/compat/pathfind.c')
-rw-r--r-- | sntp/libopts/compat/pathfind.c | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/sntp/libopts/compat/pathfind.c b/sntp/libopts/compat/pathfind.c new file mode 100644 index 0000000..6554533 --- /dev/null +++ b/sntp/libopts/compat/pathfind.c @@ -0,0 +1,283 @@ +/* -*- Mode: C -*- */ + +/* pathfind.c --- find a FILE MODE along PATH */ + +/* Author: Gary V Vaughan <gvaughan@oranda.demon.co.uk> */ + +/* Code: */ + +static char * +pathfind( char const * path, + char const * fname, + char const * mode ); + +#include "compat.h" +#ifndef HAVE_PATHFIND +#if defined(__windows__) && !defined(__CYGWIN__) +static char * +pathfind( char const * path, + char const * fname, + char const * mode ) +{ + return strdup(fname); +} +#else + +static char* make_absolute( char const *string, char const *dot_path ); +static char* canonicalize_pathname( char *path ); +static char* extract_colon_unit( char* dir, char const *string, int *p_index ); + +/** + * local implementation of pathfind. + * @param[in] path colon separated list of directories + * @param[in] fname the name we are hunting for + * @param[in] mode the required file mode + * @returns an allocated string with the full path, or NULL + */ +static char * +pathfind( char const * path, + char const * fname, + char const * mode ) +{ + int p_index = 0; + int mode_bits = 0; + char * res_path = NULL; + char zPath[ AG_PATH_MAX + 1 ]; + + if (strchr( mode, 'r' )) mode_bits |= R_OK; + if (strchr( mode, 'w' )) mode_bits |= W_OK; + if (strchr( mode, 'x' )) mode_bits |= X_OK; + + /* + * FOR each non-null entry in the colon-separated path, DO ... + */ + for (;;) { + DIR* dirP; + char* colon_unit = extract_colon_unit( zPath, path, &p_index ); + + if (colon_unit == NULL) + break; + + dirP = opendir( colon_unit ); + + /* + * IF the directory is inaccessable, THEN next directory + */ + if (dirP == NULL) + continue; + + for (;;) { + struct dirent *entP = readdir( dirP ); + + if (entP == (struct dirent*)NULL) + break; + + /* + * IF the file name matches the one we are looking for, ... + */ + if (strcmp(entP->d_name, fname) == 0) { + char * abs_name = make_absolute(fname, colon_unit); + + /* + * Make sure we can access it in the way we want + */ + if (access(abs_name, mode_bits) >= 0) { + /* + * We can, so normalize the name and return it below + */ + res_path = canonicalize_pathname(abs_name); + } + + free(abs_name); + break; + } + } + + closedir( dirP ); + + if (res_path != NULL) + break; + } + + return res_path; +} + +/* + * Turn STRING (a pathname) into an absolute pathname, assuming that + * DOT_PATH contains the symbolic location of `.'. This always returns + * a new string, even if STRING was an absolute pathname to begin with. + */ +static char* +make_absolute( char const *string, char const *dot_path ) +{ + char *result; + int result_len; + + if (!dot_path || *string == '/') { + result = strdup( string ); + } else { + if (dot_path && dot_path[0]) { + result = malloc( 2 + strlen( dot_path ) + strlen( string ) ); + strcpy( result, dot_path ); + result_len = (int)strlen(result); + if (result[result_len - 1] != '/') { + result[result_len++] = '/'; + result[result_len] = '\0'; + } + } else { + result = malloc( 3 + strlen( string ) ); + result[0] = '.'; result[1] = '/'; result[2] = '\0'; + result_len = 2; + } + + strcpy( result + result_len, string ); + } + + return result; +} + +/* + * Canonicalize PATH, and return a new path. The new path differs from + * PATH in that: + * + * Multiple `/'s are collapsed to a single `/'. + * Leading `./'s are removed. + * Trailing `/.'s are removed. + * Trailing `/'s are removed. + * Non-leading `../'s and trailing `..'s are handled by removing + * portions of the path. + */ +static char* +canonicalize_pathname( char *path ) +{ + int i, start; + char stub_char, *result; + + /* The result cannot be larger than the input PATH. */ + result = strdup( path ); + + stub_char = (*path == '/') ? '/' : '.'; + + /* Walk along RESULT looking for things to compact. */ + i = 0; + while (result[i]) { + while (result[i] != '\0' && result[i] != '/') + i++; + + start = i++; + + /* If we didn't find any slashes, then there is nothing left to + * do. + */ + if (!result[start]) + break; + + /* Handle multiple `/'s in a row. */ + while (result[i] == '/') + i++; + +#if !defined (apollo) + if ((start + 1) != i) +#else + if ((start + 1) != i && (start != 0 || i != 2)) +#endif /* apollo */ + { + strcpy( result + start + 1, result + i ); + i = start + 1; + } + + /* Handle backquoted `/'. */ + if (start > 0 && result[start - 1] == '\\') + continue; + + /* Check for trailing `/', and `.' by itself. */ + if ((start && !result[i]) + || (result[i] == '.' && !result[i+1])) { + result[--i] = '\0'; + break; + } + + /* Check for `../', `./' or trailing `.' by itself. */ + if (result[i] == '.') { + /* Handle `./'. */ + if (result[i + 1] == '/') { + strcpy( result + i, result + i + 1 ); + i = (start < 0) ? 0 : start; + continue; + } + + /* Handle `../' or trailing `..' by itself. */ + if (result[i + 1] == '.' && + (result[i + 2] == '/' || !result[i + 2])) { + while (--start > -1 && result[start] != '/') + ; + strcpy( result + start + 1, result + i + 2 ); + i = (start < 0) ? 0 : start; + continue; + } + } + } + + if (!*result) { + *result = stub_char; + result[1] = '\0'; + } + + return result; +} + +/* + * Given a string containing units of information separated by colons, + * return the next one pointed to by (P_INDEX), or NULL if there are no + * more. Advance (P_INDEX) to the character after the colon. + */ +static char* +extract_colon_unit( char* pzDir, char const *string, int *p_index ) +{ + char * pzDest = pzDir; + int ix = *p_index; + + if (string == NULL) + return NULL; + + if ((unsigned)ix >= strlen( string )) + return NULL; + + { + char const * pzSrc = string + ix; + + while (*pzSrc == ':') pzSrc++; + + for (;;) { + char ch = (*(pzDest++) = *(pzSrc++)); + switch (ch) { + case ':': + pzDest[-1] = NUL; + /* FALLTHROUGH */ + case NUL: + goto copy_done; + } + + if ((unsigned long)(pzDest - pzDir) >= AG_PATH_MAX) + break; + } copy_done:; + + ix = (int)(pzSrc - string); + } + + if (*pzDir == NUL) + return NULL; + + *p_index = ix; + return pzDir; +} +#endif /* __windows__ / __CYGWIN__ */ +#endif /* HAVE_PATHFIND */ + +/* + * Local Variables: + * mode: C + * c-file-style: "stroustrup" + * indent-tabs-mode: nil + * End: + * end of compat/pathfind.c */ |