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Fixed bugs in iso_node_cmp_flag() introduced with revision 559

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and clarified constraints for stream comparison functions in libisofs.h
This commit is contained in:
Thomas Schmitt 2009-05-18 15:33:36 +02:00
parent 714ee67472
commit b34fd35e62
2 changed files with 37 additions and 13 deletions
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16
libisofs/libisofs.h
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@ -898,9 +898,19 @@ struct IsoStream_Iface
* Compare two streams whether they are based on the same input and will
* produce the same output. If in any doubt, then this comparison should
* indicate no match. A match might allow hardlinking of IsoFile objects.
*
* This function has to establish an equivalence and order relation:
* A = A, if A = B then B = A, if A = B and B = C then A = C,
* if A < B then not B < A, if A < B and B < C then A < C
* cmp_ino(A,A) == 0
* cmp_ino(A,B) == -cmp_ino(B,A)
* if cmp_ino(A,B) == 0 && cmp_ino(B,C) == 0 then cmp_ino(A,C) == 0
* if cmp_ino(A,B) < 0 && cmp_ino(B,C) < 0 then cmp_ino(A,C) < 0
*
* A big hazard to the last constraint are tests which do not apply to some
* types of streams. In this case for any A that is applicable and any B
* that is not applicable, cmp_ino(A,B) must have the same non-zero
* result. I.e. a pair of applicable and non-applicable streams must
* return that non-zero result before the test for a pair of applicable
* streams would happen.
*
* A function s1.(*cmp_ino)() must only accept stream s2 if function
* s2.(*cmp_ino)() would accept s1. Best is to accept only the own stream
@ -2494,7 +2504,7 @@ time_t iso_node_get_ctime(const IsoNode *node);
/**
* Set if the node will be hidden in RR/ISO tree, Joliet tree or both.
*
* If the file is setted as hidden in one tree, it won't be included there, so
* If the file is set as hidden in one tree, it won't be included there, so
* it won't be visible in a OS accessing CD using that tree. For example,
* GNU/Linux systems access to Rock Ridge / ISO9960 tree in order to see
* what is recorded on CD, while MS Windows make use of the Joliet tree. If a

34
libisofs/node.c
View File

@ -2423,6 +2423,16 @@ int iso_node_set_unique_id(IsoNode *node, IsoImage *image, int flag)
/* ts A90508 */
/*
* Note to programmers: It is crucial not to break the following constraints.
* Anti-symmetry: cmp(X,Y) == - cmp(Y,X)
* Transitivity : if cmp(A,B) < 0 && cmp(B,C) < 0 then cmp(A,C) < 0
* if cmp(A,B) == 0 && cmp(B,C) == 0 then cmp(A,C) == 0
* A big transitivity hazard are tests which do not apply to some nodes.
* In this case for any A that is applicable and any B that is not applicable
* the comparison must have the same non-zero result. I.e. a pair of applicable
* and non-applicable node must return that non-zero result before the test
* for a pair of applicable nodes would happen.
*
* @param flag
* bit0= compare stat properties and attributes
* bit1= treat all nodes with image ino == 0 as unique
@ -2440,8 +2450,10 @@ int iso_node_cmp_flag(IsoNode *n1, IsoNode *n2, int flag)
if (n1 == n2)
return 0;
if (n1->type != n2->type)
return (n1->type < n2->type ? -1 : 1);
/* Imported or explicite ISO image node id has absolute priority */
/* Imported or explicite ISO image node id has priority */
ret1 = (iso_node_get_id(n1, &fs_id1, &dev_id1, &ino_id1, 1) > 0);
ret2 = (iso_node_get_id(n2, &fs_id2, &dev_id2, &ino_id2, 1) > 0);
if (ret1 != ret2)
@ -2452,11 +2464,10 @@ int iso_node_cmp_flag(IsoNode *n1, IsoNode *n2, int flag)
*/
if (ino_id1 != ino_id2)
return (ino_id1 < ino_id2 ? -1 : 1);
goto inode_match;
if (ino_id1 == 0) /* Image ino 0 is always unique */
return (n1 < n2 ? -1 : 1);
goto image_inode_match;
}
if (n1->type != n2->type)
return (n1->type < n2->type ? -1 : 1);
if (n1->type == LIBISO_FILE) {
@ -2506,13 +2517,16 @@ int iso_node_cmp_flag(IsoNode *n1, IsoNode *n2, int flag)
return (n1 < n2 ? -1 : 1);
inode_match:;
if (flag & 2) {
iso_node_get_id(n1, &fs_id1, &dev_id1, &ino_id1, 1);
iso_node_get_id(n2, &fs_id2, &dev_id2, &ino_id2, 1);
if (ino_id1 == 0 || ino_id2 == 0)
return (n1 < n2 ? -1 : 1);
/* What comes here has no predefined image ino resp. image_ino == 0 .
Regard this as not equal.
*/
return (n1 < n2 ? -1 : 1);
}
image_inode_match:;
if (!(flag & 1))
return 0;
if (n1->type == LIBISO_SYMLINK) {
@ -2566,5 +2580,5 @@ inode_match:;
/* API */
int iso_node_cmp_ino(IsoNode *n1, IsoNode *n2, int flag)
{
return iso_node_cmp_flag(n1, n2, 1 | 2);
return iso_node_cmp_flag(n1, n2, 1);
}