/* A rather quick hack to open a file via a path -- could be made more general. Would prefer to use a standard one out of a library but there doesn't seem to be one... Seems to cover all the bases -- elements of path may end in '/' if that's your style; absolute (rooted) filenames do not go via path, and '.' works OK. I would prefer not to do the open() in this code but I suppose I have to worry about efficiency. [I would prefer not to do the open because I might want to find a file for reading via FILE * instead, or for some other reason that opening it.] pathopen( "PATHNAME", Open a dictionary file via PATHNAME default path, what to use if PATHNAME not found include file name, eg "linux.inc", or "math" etc. extension, "inc" for an include file at the moment. &expanded name) Fills in full name with path and extension. -> int file descriptor or -1 for not found. If you want to do a FILE * open, do the pathopen first, and if it succeeds, either close the fd and reopen a FILE * using the updated filename, *or* use fdopen on the returned fd. ( FILE *fdopen(int fd, const char *mode); ) *HOWEVER* fdopen of an fd opened for write does *not* reset the file the way fopen with "w" does, so is unwise to use if writing to an existing file. Fortunately this is not an issue for reading include files. */ #define _POSIX_C_SOURCE 200809L #define _XOPEN_SOURCE 500 #include #include #include #include // for close() #include int pathopen_debug = (0 == 0); /* Generic Unix thingummybobs - could put inline but it's easier for me to test at home on my Archimedes if I make it portable... */ #define DIRSEP "/" #define EXTSEPCH '.' #define PATHSEPCH ':' #define ROOT "/" #define HOME "." /* To catch non-path names ./fred & ../fred */ #define HERE "./" int getpath_debug = (0 != 0); /* May be tweaked by debugger */ static int absolute(char *fname) { /* Don't look in path if absolute filename * given */ /* This could easily be a macro, but I've made it a function so that * it can more easily be expanded later. (For instance, on the * Archimedes it is quite a hassle to work out whether a filename is * absolute...) */ if (strncmp(fname, ROOT, strlen(ROOT)) == 0) return (0 == 0); if (strncmp(fname, HOME, strlen(HOME)) == 0) return (0 == 0); return (0 != 0); } int pathopen(char *pathname, char *defpath, char *basename, char *ext, char **fullnamep) { #define NULLEXIT(p) if (p == NULL) exit(EXIT_FAILURE); else /* OK */ #define fullname (*fullnamep) char *dictp = NULL, *dictpath = NULL; char *sep = NULL, *place = NULL; char *filename = NULL; char *savepath = NULL, *savefile = NULL; int f = -1; dictp = ""; if (absolute(basename) || (dictp = getenv(pathname)) != NULL) { savepath = dictpath = malloc(strlen(dictp) + 1); NULLEXIT(dictpath); strcpy(dictpath, dictp); } else { savepath = dictpath = malloc(strlen(defpath) + 1); NULLEXIT(dictpath); strcpy(dictpath, defpath); } for (;;) { sep = strchr(dictpath, PATHSEPCH); if (sep == NULL) { /* last element of path */ place = dictpath; dictpath = dictpath + strlen(dictpath); } else { /* More to come */ place = dictpath; *sep = '\0'; dictpath = sep + 1; } if (*place == '\0') { /* "/usr/share/dict:/usr/dict:" -- * last ":" implies current dir */ savefile = filename = malloc(strlen(basename) + 1); NULLEXIT(filename); strcpy(filename, basename); } else { /* Use given path. Allow it to be of the form * "/usr/dict/" */ if (*place == '~') { char newplace[1024]; sprintf(newplace, "%s%s", getenv("HOME")?:"", place+1); place = strdup(newplace); } //fprintf(stderr, "Looking in %s\n", place); if (strncmp(place + strlen(place) - strlen(DIRSEP), DIRSEP, strlen(DIRSEP)) == 0) { savefile = filename = malloc(strlen(place) + strlen(basename) + 1); NULLEXIT(filename); sprintf(filename, "%s%s", place, basename); } else { savefile = filename = malloc(strlen(place) + strlen(DIRSEP) + strlen(basename) + 1); NULLEXIT(filename); sprintf(filename, "%s%s%s", place, DIRSEP, basename); } } if (strncmp(filename, HERE, strlen(HERE)) == 0) { /* For tidyness, strip * leading "./" */ filename += strlen(HERE); } if (strrchr(filename, EXTSEPCH) == NULL && ext != NULL) { /* If no extension given, add default */ char *fileext = malloc(strlen(filename) + 1 + strlen(ext) + 1); NULLEXIT(fileext); sprintf(fileext, "%s%c%s", filename, EXTSEPCH, ext); free(savefile); savefile = filename = fileext; } if (getpath_debug) if (pathopen_debug) fprintf(stderr, "Looking for %s\n", filename); if ((f = open(filename, O_RDONLY)) != -1) { fullname = filename; /* Returns a mallocked string */ free(savepath); return (f); /* return the fd of the file */ } if (sep == NULL && *dictpath == '\0') break; } free(savefile); free(savepath); fullname = NULL; return (-1); /* could not open the file */ #undef NULLEXIT #undef fullname } // Only used if environment variable doesn't exist. #define IMP_INC_PATH "/usr/local/include/i2c:." char *fullpath(char *filename) { char *fullname; int fd; fd = pathopen("IMP_INC_PATH", IMP_INC_PATH, filename, "inc", &fullname); //fprintf(stderr, "pathopen(\"IMP_INC_PATH\", \"%s\", \"%s\", \"inc\", -> ", getenv("IMP_INC_PATH") ?: IMP_INC_PATH, filename); if (fd != -1) { //fprintf(stderr, "\"%s\") -> %d\n", fullname, fd); close(fd); return strdup(fullname); } else { //fprintf(stderr, "NULL) -> -1\n"); return strdup(filename); // already an imp string } } #ifdef DBMAIN int main(int argc, char **argv) { char *fullname; int fd; if (argc != 2) { fprintf(stderr, "syntax: pathopen includefile\n"); exit(EXIT_FAILURE); } getpath_debug = (0 == 0); fd = pathopen("IMP_INC_PATH", IMP_INC_PATH, argv[1], "inc", &fullname); fprintf(stderr, "pathopen(\"IMP_INC_PATH\", \"%s\", \"%s\", \"inc\", -> ", IMP_INC_PATH, argv[1]); if (fd != -1) { fprintf(stderr, "\"%s\") -> %d\n", fullname, fd); free(fullname); } else { fprintf(stderr, "NULL) -> -1\n"); } } #endif /* DBMAIN */