1CHMOD(2) 386BSD Programmer's Manual CHMOD(2) 2 3NNAAMMEE 4 cchhmmoodd, ffcchhmmoodd - change mode of file 5 6SSYYNNOOPPSSIISS 7 ##iinncclluuddee <<ssyyss//ssttaatt..hh>> 8 9 _i_n_t 10 cchhmmoodd(_c_o_n_s_t _c_h_a_r *_p_a_t_h, _m_o_d_e__t _m_o_d_e) 11 12 _i_n_t 13 ffcchhmmoodd(_i_n_t _f_d, _m_o_d_e__t _m_o_d_e) 14 15DDEESSCCRRIIPPTTIIOONN 16 The function cchhmmoodd() sets the file permission bits of the file specified 17 by the pathname _p_a_t_h to _m_o_d_e. FFcchhmmoodd() sets the permission bits of the 18 specified file descriptor _f_d. CChhmmoodd() verifies that the process owner 19 (user) either owns the file specified by _p_a_t_h (or _f_d), or is the super- 20 user. A mode is created from _o_r'd permission bit masks defined in 21 <_s_y_s/_s_t_a_t._h>: 22 #define S_IRWXU 0000700 /* RWX mask for owner */ 23 #define S_IRUSR 0000400 /* R for owner */ 24 #define S_IWUSR 0000200 /* W for owner */ 25 #define S_IXUSR 0000100 /* X for owner */ 26 27 #define S_IRWXG 0000070 /* RWX mask for group */ 28 #define S_IRGRP 0000040 /* R for group */ 29 #define S_IWGRP 0000020 /* W for group */ 30 #define S_IXGRP 0000010 /* X for group */ 31 32 #define S_IRWXO 0000007 /* RWX mask for other */ 33 #define S_IROTH 0000004 /* R for other */ 34 #define S_IWOTH 0000002 /* W for other */ 35 #define S_IXOTH 0000001 /* X for other */ 36 37 #define S_ISUID 0004000 /* set user id on execution */ 38 #define S_ISGID 0002000 /* set group id on execution */ 39 #define S_ISVTX 0001000 /* save swapped text even after use */ 40 41 The ISVTX (the _s_t_i_c_k_y _b_i_t) indicates to the system which executable files 42 are shareable (the default) and the system maintains the program text of 43 the files in the swap area. The sticky bit may only be set by the super 44 user on shareable executable files. 45 46 If mode ISVTX (the `sticky bit') is set on a directory, an unprivileged 47 user may not delete or rename files of other users in that directory. The 48 sticky bit may be set by any user on a directory which the user owns or 49 has appropriate permissions. For more details of the properties of the 50 sticky bit, see sticky(8). 51 52 Writing or changing the owner of a file turns off the set-user-id and 53 set-group-id bits unless the user is the super-user. This makes the 54 system somewhat more secure by protecting set-user-id (set-group-id) 55 files from remaining set-user-id (set-group-id) if they are modified, at 56 the expense of a degree of compatibility. 57 58RREETTUURRNN VVAALLUUEESS 59 Upon successful completion, a value of 0 is returned. Otherwise, a value 60 of -1 is returned and _e_r_r_n_o is set to indicate the error. 61 62EERRRROORRSS 63 CChhmmoodd() will fail and the file mode will be unchanged if: 64 65 66 [ENOTDIR] A component of the path prefix is not a directory. 67 68 [EINVAL] The pathname contains a character with the high-order bit 69 set. 70 71 [ENAMETOOLONG] 72 A component of a pathname exceeded 255 characters, or an 73 entire path name exceeded 1023 characters. 74 75 [ENOENT] The named file does not exist. 76 77 [EACCES] Search permission is denied for a component of the path 78 prefix. 79 80 [ELOOP] Too many symbolic links were encountered in translating the 81 pathname. 82 83 [EPERM] The effective user ID does not match the owner of the file 84 and the effective user ID is not the super-user. 85 86 [EROFS] The named file resides on a read-only file system. 87 88 [EFAULT] _P_a_t_h points outside the process's allocated address space. 89 90 [EIO] An I/O error occurred while reading from or writing to the 91 file system. 92 93 FFcchhmmoodd() will fail if: 94 95 [EBADF] The descriptor is not valid. 96 97 [EINVAL] _F_d refers to a socket, not to a file. 98 99 [EROFS] The file resides on a read-only file system. 100 101 [EIO] An I/O error occurred while reading from or writing to the 102 file system. 103 104SSEEEE AALLSSOO 105 chmod(1), open(2), chown(2), stat(2), sticky(8) 106 107SSTTAANNDDAARRDDSS 108 CChhmmoodd() is expected to conform to IEEE Std 1003.1-1988 (``POSIX''). 109 110HHIISSTTOORRYY 111 The ffcchhmmoodd() function call appeared in 4.2BSD. 112 1134th Berkeley Distribution March 10, 1991 2 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133