1 /* 2 * Copyright (c) 1985 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #ifndef lint 8 static char sccsid[] = "@(#)tftpsubs.c 5.1 (Berkeley) 02/06/86"; 9 #endif not lint 10 11 /* Simple minded read-ahead/write-behind subroutines for tftp user and 12 server. Written originally with multiple buffers in mind, but current 13 implementation has two buffer logic wired in. 14 15 Todo: add some sort of final error check so when the write-buffer 16 is finally flushed, the caller can detect if the disk filled up 17 (or had an i/o error) and return a nak to the other side. 18 19 Jim Guyton 10/85 20 */ 21 22 #include <sys/types.h> 23 #include <sys/socket.h> 24 #include <netinet/in.h> 25 #include <arpa/tftp.h> 26 #include <stdio.h> 27 28 #define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */ 29 30 struct bf { 31 int counter; /* size of data in buffer, or flag */ 32 char buf[PKTSIZE]; /* room for data packet */ 33 } bfs[2]; 34 35 /* Values for bf.counter */ 36 #define BF_ALLOC -3 /* alloc'd but not yet filled */ 37 #define BF_FREE -2 /* free */ 38 /* [-1 .. SEGSIZE] = size of data in the data buffer */ 39 40 static int nextone; /* index of next buffer to use */ 41 static int current; /* index of buffer in use */ 42 43 /* control flags for crlf conversions */ 44 int newline = 0; /* fillbuf: in middle of newline expansion */ 45 int prevchar = -1; /* putbuf: previous char (cr check) */ 46 47 struct tftphdr *rw_init(); 48 49 struct tftphdr *w_init() { return rw_init(0); } /* write-behind */ 50 struct tftphdr *r_init() { return rw_init(1); } /* read-ahead */ 51 52 struct tftphdr * 53 rw_init(x) /* init for either read-ahead or write-behind */ 54 int x; /* zero for write-behind, one for read-head */ 55 { 56 newline = 0; /* init crlf flag */ 57 prevchar = -1; 58 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */ 59 current = 0; 60 bfs[1].counter = BF_FREE; 61 nextone = x; /* ahead or behind? */ 62 return (struct tftphdr *)bfs[0].buf; 63 } 64 65 66 /* Have emptied current buffer by sending to net and getting ack. 67 Free it and return next buffer filled with data. 68 */ 69 readit(file, dpp, convert) 70 FILE *file; /* file opened for read */ 71 struct tftphdr **dpp; 72 int convert; /* if true, convert to ascii */ 73 { 74 struct bf *b; 75 76 bfs[current].counter = BF_FREE; /* free old one */ 77 current = !current; /* "incr" current */ 78 79 b = &bfs[current]; /* look at new buffer */ 80 if (b->counter == BF_FREE) /* if it's empty */ 81 read_ahead(file, convert); /* fill it */ 82 /* assert(b->counter != BF_FREE); /* check */ 83 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */ 84 return b->counter; 85 } 86 87 /* 88 * fill the input buffer, doing ascii conversions if requested 89 * conversions are lf -> cr,lf and cr -> cr, nul 90 */ 91 read_ahead(file, convert) 92 FILE *file; /* file opened for read */ 93 int convert; /* if true, convert to ascii */ 94 { 95 register int i; 96 register char *p; 97 register int c; 98 struct bf *b; 99 struct tftphdr *dp; 100 101 b = &bfs[nextone]; /* look at "next" buffer */ 102 if (b->counter != BF_FREE) /* nop if not free */ 103 return; 104 nextone = !nextone; /* "incr" next buffer ptr */ 105 106 dp = (struct tftphdr *)b->buf; 107 108 if (convert == 0) { 109 b->counter = read(fileno(file), dp->th_data, SEGSIZE); 110 return; 111 } 112 113 p = dp->th_data; 114 for (i = 0 ; i < SEGSIZE; i++) { 115 if (newline) { 116 if (prevchar == '\n') 117 c = '\n'; /* lf to cr,lf */ 118 else c = '\0'; /* cr to cr,nul */ 119 newline = 0; 120 } 121 else { 122 c = getc(file); 123 if (c == EOF) break; 124 if (c == '\n' || c == '\r') { 125 prevchar = c; 126 c = '\r'; 127 newline = 1; 128 } 129 } 130 *p++ = c; 131 } 132 b->counter = (int)(p - dp->th_data); 133 } 134 135 /* Update count associated with the buffer, get new buffer 136 from the queue. Calls write_behind only if next buffer not 137 available. 138 */ 139 writeit(file, dpp, ct, convert) 140 FILE *file; 141 struct tftphdr **dpp; 142 int convert; 143 { 144 bfs[current].counter = ct; /* set size of data to write */ 145 current = !current; /* switch to other buffer */ 146 if (bfs[current].counter != BF_FREE) /* if not free */ 147 write_behind(file, convert); /* flush it */ 148 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */ 149 *dpp = (struct tftphdr *)bfs[current].buf; 150 return ct; /* this is a lie of course */ 151 } 152 153 /* 154 * Output a buffer to a file, converting from netascii if requested. 155 * CR,NUL -> CR and CR,LF => LF. 156 * Note spec is undefined if we get CR as last byte of file or a 157 * CR followed by anything else. In this case we leave it alone. 158 */ 159 write_behind(file, convert) 160 FILE *file; 161 int convert; 162 { 163 char *buf; 164 int count; 165 register int ct; 166 register char *p; 167 register int c; /* current character */ 168 struct bf *b; 169 struct tftphdr *dp; 170 171 b = &bfs[nextone]; 172 if (b->counter < -1) /* anything to flush? */ 173 return 0; /* just nop if nothing to do */ 174 175 count = b->counter; /* remember byte count */ 176 b->counter = BF_FREE; /* reset flag */ 177 dp = (struct tftphdr *)b->buf; 178 nextone = !nextone; /* incr for next time */ 179 buf = dp->th_data; 180 181 if (count <= 0) return -1; /* nak logic? */ 182 183 if (convert == 0) 184 return write(fileno(file), buf, count); 185 186 p = buf; 187 ct = count; 188 while (ct--) { /* loop over the buffer */ 189 c = *p++; /* pick up a character */ 190 if (prevchar == '\r') { /* if prev char was cr */ 191 if (c == '\n') /* if have cr,lf then just */ 192 fseek(file, -1, 1); /* smash lf on top of the cr */ 193 else 194 if (c == '\0') /* if have cr,nul then */ 195 goto skipit; /* just skip over the putc */ 196 /* else just fall through and allow it */ 197 } 198 putc(c, file); 199 skipit: 200 prevchar = c; 201 } 202 return count; 203 } 204 205 206