1 /* 2 * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers. 3 * All rights reserved. 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * By using this file, you agree to the terms and conditions set 11 * forth in the LICENSE file which can be found at the top level of 12 * the sendmail distribution. 13 */ 14 15 #include <sm/gen.h> 16 SM_RCSID("@(#)$Id: refill.c,v 1.49 2001/09/11 04:04:49 gshapiro Exp $") 17 #include <stdlib.h> 18 #include <unistd.h> 19 #include <errno.h> 20 #include <setjmp.h> 21 #include <signal.h> 22 #include <sys/time.h> 23 #include <fcntl.h> 24 #include <string.h> 25 #include <sm/io.h> 26 #include <sm/conf.h> 27 #include <sm/assert.h> 28 #include "local.h" 29 30 static int sm_lflush __P((SM_FILE_T *, int *)); 31 32 /* 33 ** SM_IO_RD_TIMEOUT -- measured timeout for reads 34 ** 35 ** This #define uses a select() to wait for the 'fd' to become readable. 36 ** The select() can be active for up to 'To' time. The select() may not 37 ** use all of the the 'To' time. Hence, the amount of "wall-clock" time is 38 ** measured to decide how much to subtract from 'To' to update it. On some 39 ** BSD-based/like systems the timeout for a select() is updated for the 40 ** amount of time used. On many/most systems this does not happen. Therefore 41 ** the updating of 'To' must be done ourselves; a copy of 'To' is passed 42 ** since a BSD-like system will have updated it and we don't want to 43 ** double the time used! 44 ** Note: if a valid 'fd' doesn't exist yet, don't use this (e.g. the 45 ** sendmail buffered file type in sendmail/bf.c; see use below). 46 ** 47 ** Parameters 48 ** fp -- the file pointer for the active file 49 ** fd -- raw file descriptor (from 'fp') to use for select() 50 ** to -- struct timeval of the timeout 51 ** timeout -- the original timeout value 52 ** sel_ret -- the return value from the select() 53 ** 54 ** Returns: 55 ** nothing, flow through code 56 */ 57 58 #define SM_IO_RD_TIMEOUT(fp, fd, to, timeout, sel_ret) \ 59 { \ 60 struct timeval sm_io_to_before, sm_io_to_after, sm_io_to_diff; \ 61 fd_set sm_io_to_mask, sm_io_x_mask; \ 62 errno = 0; \ 63 if (timeout == SM_TIME_IMMEDIATE) \ 64 { \ 65 errno = EAGAIN; \ 66 return SM_IO_EOF; \ 67 } \ 68 FD_ZERO(&sm_io_to_mask); \ 69 FD_SET((fd), &sm_io_to_mask); \ 70 FD_ZERO(&sm_io_x_mask); \ 71 FD_SET((fd), &sm_io_x_mask); \ 72 if (gettimeofday(&sm_io_to_before, NULL) < 0) \ 73 return SM_IO_EOF; \ 74 (sel_ret) = select((fd) + 1, &sm_io_to_mask, NULL, \ 75 &sm_io_x_mask, (to)); \ 76 if ((sel_ret) < 0) \ 77 { \ 78 /* something went wrong, errno set */ \ 79 fp->f_r = 0; \ 80 fp->f_flags |= SMERR; \ 81 return SM_IO_EOF; \ 82 } \ 83 else if ((sel_ret) == 0) \ 84 { \ 85 /* timeout */ \ 86 errno = EAGAIN; \ 87 return SM_IO_EOF; \ 88 } \ 89 /* calulate wall-clock time used */ \ 90 if (gettimeofday(&sm_io_to_after, NULL) < 0) \ 91 return SM_IO_EOF; \ 92 timersub(&sm_io_to_before, &sm_io_to_after, &sm_io_to_diff); \ 93 timersub((to), &sm_io_to_diff, (to)); \ 94 } 95 96 /* 97 ** SM_LFLUSH -- flush a file if it is line buffered and writable 98 ** 99 ** Parameters: 100 ** fp -- file pointer to flush 101 ** timeout -- original timeout value (in milliseconds) 102 ** 103 ** Returns: 104 ** Failure: returns SM_IO_EOF and sets errno 105 ** Success: returns 0 106 */ 107 108 static int 109 sm_lflush(fp, timeout) 110 SM_FILE_T *fp; 111 int *timeout; 112 { 113 114 if ((fp->f_flags & (SMLBF|SMWR)) == (SMLBF|SMWR)) 115 return sm_flush(fp, timeout); 116 return 0; 117 } 118 119 /* 120 ** SM_REFILL -- refill a buffer 121 ** 122 ** Parameters: 123 ** fp -- file pointer for buffer refill 124 ** timeout -- time to complete filling the buffer in milliseconds 125 ** 126 ** Returns: 127 ** Success: returns 0 128 ** Failure: returns SM_IO_EOF 129 */ 130 131 int 132 sm_refill(fp, timeout) 133 register SM_FILE_T *fp; 134 int timeout; 135 { 136 int ret, r; 137 struct timeval to; 138 int fd; 139 140 if (timeout == SM_TIME_DEFAULT) 141 timeout = fp->f_timeout; 142 if (timeout == SM_TIME_IMMEDIATE) 143 { 144 /* 145 ** Filling the buffer will take time and we are wanted to 146 ** return immediately. And we're not EOF or ERR really. 147 ** So... the failure is we couldn't do it in time. 148 */ 149 150 errno = EAGAIN; 151 fp->f_r = 0; /* just to be sure */ 152 return 0; 153 } 154 155 /* make sure stdio is set up */ 156 if (!Sm_IO_DidInit) 157 sm_init(); 158 159 fp->f_r = 0; /* largely a convenience for callers */ 160 161 if (fp->f_flags & SMFEOF) 162 return SM_IO_EOF; 163 164 SM_CONVERT_TIME(fp, fd, timeout, &to); 165 166 /* if not already reading, have to be reading and writing */ 167 if ((fp->f_flags & SMRD) == 0) 168 { 169 if ((fp->f_flags & SMRW) == 0) 170 { 171 errno = EBADF; 172 fp->f_flags |= SMERR; 173 return SM_IO_EOF; 174 } 175 176 /* switch to reading */ 177 if (fp->f_flags & SMWR) 178 { 179 if (sm_flush(fp, &timeout)) 180 return SM_IO_EOF; 181 fp->f_flags &= ~SMWR; 182 fp->f_w = 0; 183 fp->f_lbfsize = 0; 184 } 185 fp->f_flags |= SMRD; 186 } 187 else 188 { 189 /* 190 ** We were reading. If there is an ungetc buffer, 191 ** we must have been reading from that. Drop it, 192 ** restoring the previous buffer (if any). If there 193 ** is anything in that buffer, return. 194 */ 195 196 if (HASUB(fp)) 197 { 198 FREEUB(fp); 199 if ((fp->f_r = fp->f_ur) != 0) 200 { 201 fp->f_p = fp->f_up; 202 203 /* revert blocking state */ 204 return 0; 205 } 206 } 207 } 208 209 if (fp->f_bf.smb_base == NULL) 210 sm_makebuf(fp); 211 212 /* 213 ** Before reading from a line buffered or unbuffered file, 214 ** flush all line buffered output files, per the ANSI C standard. 215 */ 216 217 if (fp->f_flags & (SMLBF|SMNBF)) 218 (void) sm_fwalk(sm_lflush, &timeout); 219 220 /* 221 ** If this file is linked to another, and we are going to hang 222 ** on the read, flush the linked file before continuing. 223 */ 224 225 if (fp->f_flushfp != NULL && 226 (*fp->f_getinfo)(fp, SM_IO_IS_READABLE, NULL) <= 0) 227 sm_flush(fp->f_flushfp, &timeout); 228 229 fp->f_p = fp->f_bf.smb_base; 230 231 /* 232 ** The do-while loop stops trying to read when something is read 233 ** or it appears that the timeout has expired before finding 234 ** something available to be read (via select()). 235 */ 236 237 ret = 0; 238 do 239 { 240 errno = 0; /* needed to ensure EOF correctly found */ 241 r = (*fp->f_read)(fp, (char *)fp->f_p, fp->f_bf.smb_size); 242 if (r <= 0) 243 { 244 if (r == 0 && errno == 0) 245 break; /* EOF found */ 246 if (IS_IO_ERROR(fd, r, timeout)) 247 goto err; /* errno set */ 248 249 /* read would block */ 250 SM_IO_RD_TIMEOUT(fp, fd, &to, timeout, ret); 251 } 252 } while (r <= 0 && ret > 0); 253 254 err: 255 if (r <= 0) 256 { 257 if (r == 0) 258 fp->f_flags |= SMFEOF; 259 else 260 fp->f_flags |= SMERR; 261 fp->f_r = 0; 262 return SM_IO_EOF; 263 } 264 fp->f_r = r; 265 return 0; 266 } 267 268 /* 269 ** SM_RGET -- refills buffer and returns first character 270 ** 271 ** Handle sm_getc() when the buffer ran out: 272 ** Refill, then return the first character in the newly-filled buffer. 273 ** 274 ** Parameters: 275 ** fp -- file pointer to work on 276 ** timeout -- time to complete refill 277 ** 278 ** Returns: 279 ** Success: first character in refilled buffer as an int 280 ** Failure: SM_IO_EOF 281 */ 282 283 int 284 sm_rget(fp, timeout) 285 register SM_FILE_T *fp; 286 int timeout; 287 { 288 if (sm_refill(fp, timeout) == 0) 289 { 290 fp->f_r--; 291 return *fp->f_p++; 292 } 293 return SM_IO_EOF; 294 } 295