* [U-Boot] sprintf side effect, a bug? @ 2009-01-26 20:53 E Robertson 2009-01-26 22:30 ` Wolfgang Denk 0 siblings, 1 reply; 5+ messages in thread From: E Robertson @ 2009-01-26 20:53 UTC (permalink / raw) To: u-boot Hi, It seems that sprintf() is modifying at least two bytes from the source and I have duplicate this with different varibles. For instance, I have a mac address defined as unsigned char [6]: Doing the following sets the environment variable correctly, however bytes [0] and [1], are modified at the source. sprintf(env_ethaddr,"%02X:%02X:%02X:%02X:%02X:%02X", MACAddress[0], MACAddress[1], MACAddress[2], MACAddress[3], MACAddress[4], MACAddress[5]); Has anyone noticed this before? I don't think the machine matters but I am building for an arm at91. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. Url : http://lists.denx.de/pipermail/u-boot/attachments/20090126/68e825fd/attachment.pgp ^ permalink raw reply [flat|nested] 5+ messages in thread
* [U-Boot] sprintf side effect, a bug? 2009-01-26 20:53 [U-Boot] sprintf side effect, a bug? E Robertson @ 2009-01-26 22:30 ` Wolfgang Denk 2009-01-27 20:19 ` E Robertson 0 siblings, 1 reply; 5+ messages in thread From: Wolfgang Denk @ 2009-01-26 22:30 UTC (permalink / raw) To: u-boot Dear E Robertson, In message <200901261453.10434.e.robertson.svg@gmail.com> you wrote: > > It seems that sprintf() is modifying at least two bytes from the source and I > have duplicate this with different varibles. > For instance, I have a mac address defined as unsigned char [6]: > Doing the following sets the environment variable correctly, however bytes [0] > and [1], are modified at the source. > > sprintf(env_ethaddr,"%02X:%02X:%02X:%02X:%02X:%02X", MACAddress[0], > MACAddress[1], > MACAddress[2], MACAddress[3], > MACAddress[4], MACAddress[5]); > > Has anyone noticed this before? > I don't think the machine matters but I am building for an arm at91. Hmm... I think I wouldbe surprised. What exactly does your test code look like? I tried this one: ... unsigned char buf[128]; unsigned char a[6] = { 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, }; int i; ... printf ("Before: "); for (i=0; i<6; ++i) printf (" %02X",a[i]); putc ('\n'); sprintf (buf, "%02X:%02X:%02X:%02X:%02X:%02X", a[0], a[1], a[2], a[3], a[4], a[5]); printf ("After: "); for (i=0; i<6; ++i) printf (" %02X",a[i]); putc ('\n'); printf ("buf=\"%s\"\n", buf); ... And this is what I got: Before: 11 22 33 44 55 66 After: 11 22 33 44 55 66 buf="11:22:33:44:55:66" Looks sane to me... Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de "Anyone attempting to generate random numbers by deterministic means is, of course, living in a state of sin." - John Von Neumann ^ permalink raw reply [flat|nested] 5+ messages in thread
* [U-Boot] sprintf side effect, a bug? 2009-01-26 22:30 ` Wolfgang Denk @ 2009-01-27 20:19 ` E Robertson 2009-01-27 20:31 ` Scott Wood 0 siblings, 1 reply; 5+ messages in thread From: E Robertson @ 2009-01-27 20:19 UTC (permalink / raw) To: u-boot On Monday 26 January 2009 04:30:36 pm Wolfgang Denk wrote: > Dear E Robertson, > > In message <200901261453.10434.e.robertson.svg@gmail.com> you wrote: > > It seems that sprintf() is modifying at least two bytes from the source > > and I have duplicate this with different varibles. > > For instance, I have a mac address defined as unsigned char [6]: > > Doing the following sets the environment variable correctly, however > > bytes [0] and [1], are modified at the source. > > > > sprintf(env_ethaddr,"%02X:%02X:%02X:%02X:%02X:%02X", MACAddress[0], > > MACAddress[1], > > MACAddress[2], MACAddress[3], > > MACAddress[4], MACAddress[5]); > > > > Has anyone noticed this before? > > I don't think the machine matters but I am building for an arm at91. > > Hmm... I think I wouldbe surprised. What exactly does your test code > look like? > > I tried this one: > > ... > unsigned char buf[128]; > unsigned char a[6] = { 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, }; > int i; > ... > printf ("Before: "); for (i=0; i<6; ++i) printf (" %02X",a[i]); putc > ('\n'); sprintf (buf, "%02X:%02X:%02X:%02X:%02X:%02X", a[0], a[1], a[2], > a[3], a[4], a[5]); printf ("After: "); for (i=0; i<6; ++i) printf (" > %02X",a[i]); putc ('\n'); printf ("buf=\"%s\"\n", buf); > ... > > And this is what I got: > > Before: 11 22 33 44 55 66 > After: 11 22 33 44 55 66 > buf="11:22:33:44:55:66" > Hi, I did the following: memcpy (gd->bd->bi_enetaddr, MACAddress, sizeof(gd->bd->bi_enetaddr)); memcpy (dupMACAddress, MACAddress, sizeof(dupMACAddress)); printf("Before %02X:%02X:%02X:%02X:%02X:%02X\n",dupMACAddress[0], dupMACAddress[1], dupMACAddress[2], dupMACAddress[3], dupMACAddress[4], dupMACAddress[5]); sprintf(env_ethaddr,"%02X:%02X:%02X:%02X:%02X:%02X",dupMACAddress[0], dupMACAddress[1], dupMACAddress[2], dupMACAddress[3], dupMACAddress[4], dupMACAddress[5]); printf("After %02X:%02X:%02X:%02X:%02X:%02X\n",dupMACAddress[0], dupMACAddress[1], dupMACAddress[2], dupMACAddress[3], dupMACAddress[4], dupMACAddress[5]); printf("ethaddr %02X:%02X:%02X:%02X:%02X:%02X\n",gd->bd->bi_enetaddr[0], gd->bd->bi_enetaddr[1], gd->bd->bi_enetaddr[2], gd->bd->bi_enetaddr[3], gd->bd->bi_enetaddr[4], gd->bd->bi_enetaddr[5]); and I got this: Before 00:04:A6:00:6A:E6 After 36:00:A6:00:6A:E6 ethaddr 00:04:A6:00:6A:E6 Alse env_ethaddr has the correct correct. I make a duplicate before did the sprintf. I'm also on v 1.3.4 and haven't tried it on the latest git. > > Looks sane to me... > > Best regards, > > Wolfgang Denk -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. Url : http://lists.denx.de/pipermail/u-boot/attachments/20090127/2a0e2f89/attachment.pgp ^ permalink raw reply [flat|nested] 5+ messages in thread
* [U-Boot] sprintf side effect, a bug? 2009-01-27 20:19 ` E Robertson @ 2009-01-27 20:31 ` Scott Wood 2009-01-27 20:57 ` E Robertson 0 siblings, 1 reply; 5+ messages in thread From: Scott Wood @ 2009-01-27 20:31 UTC (permalink / raw) To: u-boot E Robertson wrote: > I did the following: > memcpy (gd->bd->bi_enetaddr, MACAddress, sizeof(gd->bd->bi_enetaddr)); > memcpy (dupMACAddress, MACAddress, sizeof(dupMACAddress)); > > printf("Before %02X:%02X:%02X:%02X:%02X:%02X\n",dupMACAddress[0], > dupMACAddress[1], > dupMACAddress[2], dupMACAddress[3], > dupMACAddress[4], dupMACAddress[5]); > > sprintf(env_ethaddr,"%02X:%02X:%02X:%02X:%02X:%02X",dupMACAddress[0], > dupMACAddress[1], > dupMACAddress[2], dupMACAddress[3], > dupMACAddress[4], dupMACAddress[5]); > printf("After %02X:%02X:%02X:%02X:%02X:%02X\n",dupMACAddress[0], > dupMACAddress[1], > dupMACAddress[2], dupMACAddress[3], > dupMACAddress[4], dupMACAddress[5]); > printf("ethaddr %02X:%02X:%02X:%02X:%02X:%02X\n",gd->bd->bi_enetaddr[0], > gd->bd->bi_enetaddr[1], > gd->bd->bi_enetaddr[2], gd->bd->bi_enetaddr[3], > gd->bd->bi_enetaddr[4], gd->bd->bi_enetaddr[5]); > > > and I got this: > > Before 00:04:A6:00:6A:E6 > After 36:00:A6:00:6A:E6 > ethaddr 00:04:A6:00:6A:E6 > Alse env_ethaddr has the correct correct. Looks like you're overflowing a buffer -- 0x36 0x00 are the last two bytes of the sprintf output. Where are env_ethaddr and dupMACaddress defined? -Scott ^ permalink raw reply [flat|nested] 5+ messages in thread
* [U-Boot] sprintf side effect, a bug? 2009-01-27 20:31 ` Scott Wood @ 2009-01-27 20:57 ` E Robertson 0 siblings, 0 replies; 5+ messages in thread From: E Robertson @ 2009-01-27 20:57 UTC (permalink / raw) To: u-boot On Tuesday 27 January 2009 02:31:52 pm Scott Wood wrote: > E Robertson wrote: > > I did the following: > > memcpy (gd->bd->bi_enetaddr, MACAddress, > > sizeof(gd->bd->bi_enetaddr)); memcpy (dupMACAddress, MACAddress, > > sizeof(dupMACAddress)); > > > > printf("Before %02X:%02X:%02X:%02X:%02X:%02X\n",dupMACAddress[0], > > dupMACAddress[1], > > dupMACAddress[2], dupMACAddress[3], > > dupMACAddress[4], dupMACAddress[5]); > > > > sprintf(env_ethaddr,"%02X:%02X:%02X:%02X:%02X:%02X",dupMACAddress[0], > > dupMACAddress[1], > > dupMACAddress[2], dupMACAddress[3], > > dupMACAddress[4], dupMACAddress[5]); > > printf("After %02X:%02X:%02X:%02X:%02X:%02X\n",dupMACAddress[0], > > dupMACAddress[1], > > dupMACAddress[2], dupMACAddress[3], > > dupMACAddress[4], dupMACAddress[5]); > > printf("ethaddr > > %02X:%02X:%02X:%02X:%02X:%02X\n",gd->bd->bi_enetaddr[0], > > gd->bd->bi_enetaddr[1], > > gd->bd->bi_enetaddr[2], gd->bd->bi_enetaddr[3], > > gd->bd->bi_enetaddr[4], gd->bd->bi_enetaddr[5]); > > > > > > and I got this: > > > > Before 00:04:A6:00:6A:E6 > > After 36:00:A6:00:6A:E6 > > ethaddr 00:04:A6:00:6A:E6 > > Alse env_ethaddr has the correct correct. > > Looks like you're overflowing a buffer -- 0x36 0x00 are the last two > bytes of the sprintf output. Where are env_ethaddr and dupMACaddress > defined? > Ah!! Yes, big user error! I forgot about the string termination. Thanks. > -Scott -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 197 bytes Desc: This is a digitally signed message part. Url : http://lists.denx.de/pipermail/u-boot/attachments/20090127/01ef3c71/attachment.pgp ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2009-01-27 20:57 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2009-01-26 20:53 [U-Boot] sprintf side effect, a bug? E Robertson 2009-01-26 22:30 ` Wolfgang Denk 2009-01-27 20:19 ` E Robertson 2009-01-27 20:31 ` Scott Wood 2009-01-27 20:57 ` E Robertson
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