Description of problem: The common error of specifying the same file for both oldiso and newiso is not detected by applydeltaiso, except by an infinite loop.  This reveals two software bugs: not diagnosing the user error in the first place, and bad copying logic in processrpm() function of src/applydeltaiso.c.

"touch foo; /usr/bin/cp foo foo" as input to a shell gives "cp: `foo' and `foo' are the same file" on stderr, with shell exit status 1 [failure], and no actual copying.  applydeltaiso should perform similar detection, and if the error is detected then abandon execution with failure status.  The SAME_INODE macro in coreutils/lib/same-inode.h gives some hints.

The bad copying logic is that 0==read(fd_rpm, buf, 8192) an a .rpm file, especially when repeated many times in a row, is not detected as "no progress now, and likely none in the future".  See source excerpt in Additional Information below.


Version-Release number of selected component (if applicable):
deltaiso-3.6-0.7.20110223git.fc17.x86_64


How reproducible: every time


Steps to Reproduce:
1. cp  Fedora-17-Final.TC4-x86_64-DVD.iso  foo
2. applydeltaiso  foo  Fedora-17-Final.TC4_TC5-x86_64-DVD.diso  foo
3.
  
Actual results: Infinite loop consuming 100% CPU; console output is:
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reading 309420732 bytes from old iso...done
ImageMagick.x86_64: copying unchanged payload
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and nothing more.

Expected results: Error exit with non-zero shell status code, and message on stderr: "foo and foo are the same file"


Additional info: Running under gdb, an example traceback is:
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(gdb) bt
#0  0x00000000004022ba in fread (__stream=0x608010, __n=0x2000, __size=0x1, __ptr=0x7fffffff9e80)
    at /usr/include/bits/stdio2.h:282
#1  processrpm (fpold=fpold@entry=0x608010, ocf=ocf@entry=0x61fb10, cf=cf@entry=0x608490, nmp=nmp@entry=0x619040, 
    nmpn=nmpn@entry=0xd0f) at applydeltaiso.c:155
#2  0x0000000000401ef1 in applydelta (fpold=fpold@entry=0x608010, ocf=0x61fb10, cf=cf@entry=0x608490, 
    outdata=outdata@entry=0x7fffe4b7c010 "ER\b", outlen=outlen@entry=0x127162bc, nmp=nmp@entry=0x619040, 
    nmpn=nmpn@entry=0xd0f) at applydeltaiso.c:330
#3  0x000000000040169a in main (argc=<optimized out>, argv=<optimized out>) at applydeltaiso.c:432
(gdb) up
#1  processrpm (fpold=fpold@entry=0x608010, ocf=ocf@entry=0x61fb10, cf=cf@entry=0x608490, nmp=nmp@entry=0x619040, 
    nmpn=nmpn@entry=0xd0f) at applydeltaiso.c:155
155		  l = fread(buf, 1, l, fpold);
(gdb) l
150	
151	      len = nmp[i];
152	      while (len)
153		{
154		  l = len > sizeof(buf) ? sizeof(buf) : len;
155==>            l = fread(buf, 1, l, fpold);
156		  if (l <= 0 && ferror(fpold))
157		    {
158		      perror("unchanged copy read");
159		      exit(1);
160		    }
161		  if (ocf->write(ocf, buf, l) != l)
162		    {
163		      perror("unchanged copy write");
164		      exit(1);
165	            }
166		  len -= l;
167		}
168	      return;
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