Date: Wed, 28 Jan 2009 14:20:54 +0200 From: Danny Braniss <danny@cs.huji.ac.il> To: Channa <channa.kad@gmail.com> Cc: Christoph Mallon <christoph.mallon@gmx.de>, freebsd-current@freebsd.org Subject: Re: Jemalloc SEGV for 1MB chunk Message-ID: <E1LS9Pa-000NBW-Ct@kabab.cs.huji.ac.il> In-Reply-To: <515c64960901280401w1e1d08bfx29adc124bc749c4a@mail.gmail.com> References: <515c64960901280339m17fa9309v2e1bc3f55454ab@mail.gmail.com> <49804597.6040303@gmx.de> <515c64960901280401w1e1d08bfx29adc124bc749c4a@mail.gmail.com>
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> Hi, > Thanks for your reply. > You mean to say i should modify the test as below: > > #include <stdio.h> > #include <stdlib.h> > #include <string.h> > > > int main() > { > int i; > char *buf; > size_t size = 1048576 ; > > buf = malloc(size); > for (i = 0; i <= 1048575; i++) > buf[i] = 'a'; > buf[size]='\0'; > printf("The length of buff is : %d\n",strlen(buf)); > free(buf); > return 0; > } > > I NULL terminated the string > buf[size] = '\0' <== The last character is NULL > > But still i get a SEGV at strlen. > > Could you please tell me if my changes above are correct? > clear case of off by one. you are requesting 'size' bytes, indexing starts at 0, all the way to size-1 which is ALL the bytes you malloc'ed then you zero the size+1 byte, ah, btw, it's not strlen that is SEGV'ing. danny > Regards, > Channa > > > On 28/01/2009, Christoph Mallon <christoph.mallon@gmx.de> wrote: > > Channa schrieb: > > > > > > > Hi All, > > > I am using jemalloc.c source from FreeBSD-current source. > > > When i allocate 1MB of memory using malloc() and use it as the below > > > test shows > > > > > > #include <stdio.h> > > > #include <stdlib.h> > > > #include <string.h> > > > > > > int main() > > > { > > > int i; > > > char *buf; > > > size_t size = 1048576 ; > > > > > > buf = malloc(size); > > > for (i = 0; i < 1048576; i++) > > > buf[i] = 'a'; > > > printf("The length of buff is : %d\n",strlen(buf)); > > > free(buf); > > > return 0; > > > } > > > > > > When i try to call strlen(buf) SEGV is recived. > > > > > > This behaviour is seen when only for 1MB chunk if i allocate > > > memory lesser than 1MB no issues noticed. > > > > > > Could anyone see similar problem? > > > Is the above test wrong? > > > Or some issue with huge memory allocation in jemalloc? > > > > > > Your response will be very helpful. > > > > > > Thanks & Regards, > > > Channa > > > > > > > You did not NUL-terminate ('\0') the string. > > > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >
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