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acme: check file content before declaring file "modified since last read" Bad remote file systems can change mtime unexpectedly, and then there is the problem that git rebase and similar operations like to change the files and then change them back, modifying the mtimes but not the content. Avoid spurious Put errors on both of those by checking file content. (False positive "modified since last read" make the real ones difficult to notice.)
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  1 b3994ec5 2003-12-11 devnull #include <u.h>

  2 b3994ec5 2003-12-11 devnull #include <libc.h>

  3 b3994ec5 2003-12-11 devnull #include <draw.h>

  4 b3994ec5 2003-12-11 devnull #include <thread.h>

  5 b3994ec5 2003-12-11 devnull #include <cursor.h>

  6 b3994ec5 2003-12-11 devnull #include <mouse.h>

  7 b3994ec5 2003-12-11 devnull #include <keyboard.h>

  8 b3994ec5 2003-12-11 devnull #include <frame.h>

  9 b3994ec5 2003-12-11 devnull #include <fcall.h>

 10 b3994ec5 2003-12-11 devnull #include <plumb.h>

 11 67dbeee5 2017-10-10 rsc #include <libsec.h>

 12 b3994ec5 2003-12-11 devnull #include "dat.h"

 13 b3994ec5 2003-12-11 devnull #include "fns.h"

 14 b3994ec5 2003-12-11 devnull 

 15 b3994ec5 2003-12-11 devnull static	Block	*blist;

 16 b3994ec5 2003-12-11 devnull 

 17 b3994ec5 2003-12-11 devnull int

 18 b3994ec5 2003-12-11 devnull tempfile(void)

 19 b3994ec5 2003-12-11 devnull {

 20 b3994ec5 2003-12-11 devnull 	char buf[128];

 21 b3994ec5 2003-12-11 devnull 	int i, fd;

 22 b3994ec5 2003-12-11 devnull 

 23 b3994ec5 2003-12-11 devnull 	snprint(buf, sizeof buf, "/tmp/X%d.%.4sacme", getpid(), getuser());

 24 b3994ec5 2003-12-11 devnull 	for(i='A'; i<='Z'; i++){

 25 b3994ec5 2003-12-11 devnull 		buf[5] = i;

 26 b3994ec5 2003-12-11 devnull 		if(access(buf, AEXIST) == 0)

 27 b3994ec5 2003-12-11 devnull 			continue;

 28 b3994ec5 2003-12-11 devnull 		fd = create(buf, ORDWR|ORCLOSE|OCEXEC, 0600);

 29 b3994ec5 2003-12-11 devnull 		if(fd >= 0)

 30 b3994ec5 2003-12-11 devnull 			return fd;

 31 b3994ec5 2003-12-11 devnull 	}

 32 b3994ec5 2003-12-11 devnull 	return -1;

 33 b3994ec5 2003-12-11 devnull }

 34 b3994ec5 2003-12-11 devnull 

 35 b3994ec5 2003-12-11 devnull Disk*

 36 b3994ec5 2003-12-11 devnull diskinit()

 37 b3994ec5 2003-12-11 devnull {

 38 b3994ec5 2003-12-11 devnull 	Disk *d;

 39 b3994ec5 2003-12-11 devnull 

 40 b3994ec5 2003-12-11 devnull 	d = emalloc(sizeof(Disk));

 41 b3994ec5 2003-12-11 devnull 	d->fd = tempfile();

 42 b3994ec5 2003-12-11 devnull 	if(d->fd < 0){

 43 b3994ec5 2003-12-11 devnull 		fprint(2, "acme: can't create temp file: %r\n");

 44 b3994ec5 2003-12-11 devnull 		threadexitsall("diskinit");

 45 b3994ec5 2003-12-11 devnull 	}

 46 b3994ec5 2003-12-11 devnull 	return d;

 47 b3994ec5 2003-12-11 devnull }

 48 b3994ec5 2003-12-11 devnull 

 49 b3994ec5 2003-12-11 devnull static

 50 b3994ec5 2003-12-11 devnull uint

 51 b3994ec5 2003-12-11 devnull ntosize(uint n, uint *ip)

 52 b3994ec5 2003-12-11 devnull {

 53 b3994ec5 2003-12-11 devnull 	uint size;

 54 b3994ec5 2003-12-11 devnull 

 55 b3994ec5 2003-12-11 devnull 	if(n > Maxblock)

 56 b3994ec5 2003-12-11 devnull 		error("internal error: ntosize");

 57 b3994ec5 2003-12-11 devnull 	size = n;

 58 b3994ec5 2003-12-11 devnull 	if(size & (Blockincr-1))

 59 b3994ec5 2003-12-11 devnull 		size += Blockincr - (size & (Blockincr-1));

 60 b3994ec5 2003-12-11 devnull 	/* last bucket holds blocks of exactly Maxblock */

 61 b3994ec5 2003-12-11 devnull 	if(ip)

 62 b3994ec5 2003-12-11 devnull 		*ip = size/Blockincr;

 63 b3994ec5 2003-12-11 devnull 	return size * sizeof(Rune);

 64 b3994ec5 2003-12-11 devnull }

 65 b3994ec5 2003-12-11 devnull 

 66 b3994ec5 2003-12-11 devnull Block*

 67 b3994ec5 2003-12-11 devnull disknewblock(Disk *d, uint n)

 68 b3994ec5 2003-12-11 devnull {

 69 b3994ec5 2003-12-11 devnull 	uint i, j, size;

 70 b3994ec5 2003-12-11 devnull 	Block *b;

 71 b3994ec5 2003-12-11 devnull 

 72 b3994ec5 2003-12-11 devnull 	size = ntosize(n, &i);

 73 b3994ec5 2003-12-11 devnull 	b = d->free[i];

 74 b3994ec5 2003-12-11 devnull 	if(b)

 75 b3994ec5 2003-12-11 devnull 		d->free[i] = b->u.next;

 76 b3994ec5 2003-12-11 devnull 	else{

 77 b3994ec5 2003-12-11 devnull 		/* allocate in chunks to reduce malloc overhead */

 78 b3994ec5 2003-12-11 devnull 		if(blist == nil){

 79 b3994ec5 2003-12-11 devnull 			blist = emalloc(100*sizeof(Block));

 80 b3994ec5 2003-12-11 devnull 			for(j=0; j<100-1; j++)

 81 b3994ec5 2003-12-11 devnull 				blist[j].u.next = &blist[j+1];

 82 b3994ec5 2003-12-11 devnull 		}

 83 b3994ec5 2003-12-11 devnull 		b = blist;

 84 b3994ec5 2003-12-11 devnull 		blist = b->u.next;

 85 b3994ec5 2003-12-11 devnull 		b->addr = d->addr;

 86 219cf22d 2014-03-13 rsc 		if(d->addr+size < d->addr){

 87 219cf22d 2014-03-13 rsc 			error("temp file overflow");

 88 219cf22d 2014-03-13 rsc 		}

 89 b3994ec5 2003-12-11 devnull 		d->addr += size;

 90 b3994ec5 2003-12-11 devnull 	}

 91 b3994ec5 2003-12-11 devnull 	b->u.n = n;

 92 b3994ec5 2003-12-11 devnull 	return b;

 93 b3994ec5 2003-12-11 devnull }

 94 b3994ec5 2003-12-11 devnull 

 95 b3994ec5 2003-12-11 devnull void

 96 b3994ec5 2003-12-11 devnull diskrelease(Disk *d, Block *b)

 97 b3994ec5 2003-12-11 devnull {

 98 b3994ec5 2003-12-11 devnull 	uint i;

 99 b3994ec5 2003-12-11 devnull 

100 b3994ec5 2003-12-11 devnull 	ntosize(b->u.n, &i);

101 b3994ec5 2003-12-11 devnull 	b->u.next = d->free[i];

102 b3994ec5 2003-12-11 devnull 	d->free[i] = b;

103 b3994ec5 2003-12-11 devnull }

104 b3994ec5 2003-12-11 devnull 

105 b3994ec5 2003-12-11 devnull void

106 b3994ec5 2003-12-11 devnull diskwrite(Disk *d, Block **bp, Rune *r, uint n)

107 b3994ec5 2003-12-11 devnull {

108 b3994ec5 2003-12-11 devnull 	int size, nsize;

109 b3994ec5 2003-12-11 devnull 	Block *b;

110 b3994ec5 2003-12-11 devnull 

111 b3994ec5 2003-12-11 devnull 	b = *bp;

112 b3994ec5 2003-12-11 devnull 	size = ntosize(b->u.n, nil);

113 b3994ec5 2003-12-11 devnull 	nsize = ntosize(n, nil);

114 b3994ec5 2003-12-11 devnull 	if(size != nsize){

115 b3994ec5 2003-12-11 devnull 		diskrelease(d, b);

116 b3994ec5 2003-12-11 devnull 		b = disknewblock(d, n);

117 b3994ec5 2003-12-11 devnull 		*bp = b;

118 b3994ec5 2003-12-11 devnull 	}

119 b3994ec5 2003-12-11 devnull 	if(pwrite(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))

120 b3994ec5 2003-12-11 devnull 		error("write error to temp file");

121 b3994ec5 2003-12-11 devnull 	b->u.n = n;

122 b3994ec5 2003-12-11 devnull }

123 b3994ec5 2003-12-11 devnull 

124 b3994ec5 2003-12-11 devnull void

125 b3994ec5 2003-12-11 devnull diskread(Disk *d, Block *b, Rune *r, uint n)

126 b3994ec5 2003-12-11 devnull {

127 b3994ec5 2003-12-11 devnull 	if(n > b->u.n)

128 b3994ec5 2003-12-11 devnull 		error("internal error: diskread");

129 b3994ec5 2003-12-11 devnull 

130 b3994ec5 2003-12-11 devnull 	ntosize(b->u.n, nil);

131 b3994ec5 2003-12-11 devnull 	if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))

132 b3994ec5 2003-12-11 devnull 		error("read error from temp file");

133 b3994ec5 2003-12-11 devnull }