From maechler at stat.math.ethz.ch  Sat Jul 17 12:15:18 2004
From: maechler at stat.math.ethz.ch (maechler@stat.math.ethz.ch)
Date: Sat Jul 17 12:15:21 2004
Subject: [Rd] gsub(*, perl=TRUE) bug incl. seg.fault (PR#7108)
Message-ID: <20040717101518.CF36C108BB@slim.kubism.ku.dk>

Experimenting a bit further, I've "found" the following

1) the problem seems only gsub(), not sub()

  > sub(" ", "", "b c + d | a * b", perl=TRUE)
  [1] "bc + d | a * b"
  > gsub(" ", "", "b c + d | a * b", perl=TRUE)
  NULL

2) only if perl = TRUE, not otherwise

3) Also modifying the replacement string only slightly leads to a
  different (correct instead of bug) result:

  > gsub(" ", "", "bc + d | a * b", perl=TRUE)
  [1] "bc+d|a*b"
  > gsub(" ", "", "b c + d | a *", perl=TRUE)
  [1] "bc+d|a*"
  > gsub(" ", "", "b c + d | b", perl=TRUE)
  [1] "bc+d|b"

Whereas those give the bug as well :

  > gsub(" ", "", "b : : d : a : b", perl=TRUE)
  NULL
  > gsub(" ", "", "b : : : : a : b", perl=TRUE)
  NULL
  > gsub(" ", "", "b : : : : : : b", perl=TRUE)
  NULL
  > gsub(" ", "", "a : : : : : : a", perl=TRUE)
  NULL
but not this
  > gsub(" ", "", "b : : : : : : a", perl=TRUE)
  [1] "b::::::a"

But it's even worse :

  > gsub(" ", "", "a: 12345 :a", perl=TRUE)

  -> segmentation fault

and from "R -d gdb" :

    > gsub(" ", "", "a: 12345 :a", perl=TRUE)

    Program received signal SIGSEGV, Segmentation fault.
    hashIndex (symbol=0x8fd0060, table=0x823f2b8) at
    ../../../R/src/main/envir.c:599
    599	  if( !HASHASH(c) ) {
    (gdb) bt
    #0  hashIndex (symbol=0x8fd0060, table=0x823f2b8)
	at ../../../R/src/main/envir.c:599
    #1  0x080b145d in R_GetGlobalCache (symbol=0x1)
	at ../../../R/src/main/envir.c:656
    #2  0x080b1ac1 in findGlobalVar (symbol=0x8fd0060)
	at ../../../R/src/main/envir.c:923
    #3  0x080b8873 in Rf_eval (e=0x823f2b8, rho=0x823f014)
	at ../../../R/src/main/eval.c:329
    #4  0x080b88c9 in Rf_eval (e=0x8fd1e60, rho=0x821e540)
	at ../../../R/src/main/eval.c:354
    #5  0x080e1e0e in GetObject (cptr=0xbfffd400)
	at ../../../R/src/main/objects.c:88
    #6  0x080e2a3b in do_usemethod (call=0x84eb084, op=0x823be78, args=0x84eb0a0, 
	env=0x8fd1df0) at ../../../R/src/main/objects.c:381
    #7  0x080b8c33 in Rf_eval (e=0x84eb084, rho=0x8fd1df0)
	at ../../../R/src/main/eval.c:375
    #8  0x080b8f48 in Rf_applyClosure (call=0x8fd1eb4, op=0x84eafa4, 
	arglist=0x8fd1e44, rho=0x823f014, suppliedenv=0x821e540)
	at ../../../R/src/main/eval.c:559
    #9  0x080b89bf in Rf_eval (e=0x8fd1eb4, rho=0x823f014)
	at ../../../R/src/main/eval.c:410
    #10 0x0811b0f3 in Rf_PrintValueEnv (s=0x8fd1eb4, env=0x823f014)
	at ../../../R/src/main/print.c:775
    #11 0x080d55f1 in Rf_ReplIteration (rho=0x823f014, savestack=150798432, 
	browselevel=1, state=0x823f014) at ../../../R/src/main/main.c:254
    #12 0x080d578d in R_ReplConsole (rho=0x823f014, savestack=0, browselevel=0)
	at ../../../R/src/main/main.c:298
    #13 0x080d60d0 in run_Rmainloop () 
        at ../../../R/src/main/main.c:656
    #14 0x08147e90 in main (ac=150798432, av=0x8fd0060)
	at ../../../R/src/unix/system.c:99
    #15 0x42017589 in __libc_start_main () from /lib/i686/libc.so.6

(which is not directly helpful since  src/main/pcre.c  (where
the C source for gsub(*, perl=TRUE) resides)  isn't mentioned above.

Must be a memory allocation / mismatch / end_of_string problem
somewhere.

Martin Maechler, ETH Zurich


[Rd] gsub(*, perl=TRUE) bug incl. seg.fault (PR#7108)
maechler@stat.math.ethz.ch