1fswalk_new 2 3 SYNOPSIS 4 Create an object to walk the filesystem tree 5 6 USAGE 7 obj = fswalk_new (Ref_Type dirfunc, Ref_Type filefunc; qualifiers) 8 9 DESCRIPTION 10 The `fswalk_new' function creates an object that is useful 11 for exploring a filesystem tree. It requires two arguments that 12 are references to functions to be called when a directory or file is 13 encountered. Each of these functions is passed at least two 14 arguments: the name of the file or directory (including leading path 15 elements relative to the directory where processing started), and 16 the stat structure of the of the file or directory. Qualifiers may 17 be used to specify additional arguments. 18 19 The object's `walk' method is the one that actually walks the 20 filesystem. 21 22 The directory callback function must return an integer value that 23 indicates how it should be processed. If the function returns 0, 24 then the directory will be skipped (pruned). A positive value 25 indicates that the directory will processed. If the function 26 returns a negative value, then no further processing by the walk 27 function will take place and control will pass to the user. 28 29 The file callback function must also return an integer that 30 indicates how processing should continue. If it returns a positive 31 value, then additional files in the corresponding directory will be 32 processed. If it returns 0, then no further files or subdirectories 33 of the directory will be processed, and processing will continue to 34 take place in the parent directory. Otherwise, the return value is 35 negative, which indicates that processing should be stopped and 36 control will pass back to the caller. 37 38 QUALIFIERS 39 The following qualifiers are supported: 40 41 dargs={args...} 42 43 `dargs' is a list of additional arguments that will be added when 44 calling the directory callback function. 45 46 fargs={args...} 47 48 `fargs' is a list of additional arguments that will be added when 49 calling the file callback function. 50 51 followlinks[=val] 52 53 The `followlinks' qualifier may be used to indicate whether 54 or not directories that are symbolic links are to be followed. By 55 default, they are not. If `followlinks' is present with no 56 value, or has a non-zero value, then symbolic links will be 57 followed. Otherwise, if `followlinks' is not present, or is 58 set to 0, then directories that are symbolic links will be skipped. 59 60 METHODS 61 62 .walk (String_Type top_dir) 63 64 The `.walk' function walks the filesystem starting at the 65 specified top-level directory calling the directory and file 66 callback functions as it goes. 67 68 EXAMPLE 69 Print a list of all files containing a `.png' extension under 70 the current directory: 71 72 private define file_callback (name, st) 73 { 74 if (".png" == path_extname (name)) 75 message (name); 76 return 1; 77 } 78 variable w = fswalk_new (NULL, &file_callback); 79 w.walk ("."); 80 81 82 Get a list of all directories that are symbolic links under /usr. 83 84 private define dir_callback (name, st, list) 85 { 86 st = lstat_file (name); 87 if (stat_is ("lnk", st.st_mode)) 88 { 89 list_append (list, name); 90 return 0; 91 } 92 return 1; 93 } 94 95 define get_symdir_list (top) 96 { 97 variable list = {}; 98 variable w = fswalk_new (&dir_callback, NULL 99 ;dargs={list}, followlinks); 100 w.walk (top); 101 return list; 102 } 103 symdirlist = get_symdir_list ("/usr"); 104 105 Note that in this example, the dir_callback function returns 0 if 106 the directory corresponds to a symbolic link. This causes the link 107 to not be followed. 108 109 Get a list of dangling symbolic links: 110 111 private define file_callback (name, st, list) 112 { 113 if (stat_is ("lnk", st.st_mode)) 114 { 115 if ((NULL == stat_file (name)) 116 && (errno == ENOENT)) 117 list_append (list, name); 118 } 119 return 1; 120 } 121 122 define get_badlinks (top) 123 { 124 variable list = {}; 125 variable w = fswalk_new (NULL, &file_callback ;fargs={list}); 126 w.walk (top); 127 return list; 128 } 129 130 131 SEE ALSO 132 glob, stat_file, lstat_file, listdir; 133 134-------------------------------------------------------------- 135