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PATH_MAX (Re: [PATCH] system_path: use a static buffer)

From
Jonathan Nieder <jrnieder@gmail.com>
Date
Mar 18, 2011, 11:38 UTC
Message-ID
<20110318113818.GA6049@elie>
In-Reply-To
<AANLkTikms3Ek1CgQHg+gT8Eqs2K6PCvOB-kWZ-aqGawg@mail.gmail.com>
Hi,
Nguyen Thai Ngoc Duy wrote:
> It was pointed out elsewhere [1] that PATH_MAX only specifies max
> length of a path element, not full path. I think we'd need to stay
> away from preallocated PATH_MAX-sized arrays.

No, PATH_MAX is actually the maximum length of a path, and when you use, say, open(2), it will fail if your path is longer than that. The maximum length of a path component on most filesytems is 255 or 256; PATH_MAX on Linux is 4096.

It is indeed possible to have paths with length longer than that. The way to support that is to use relative paths wherever possible, which does sound to me like an interesting long-term goal (mostly because I suspect the result would be easier to read and, especially, to reason about with respect to race conditions).

Hope that helps, Jonathan

Previous: Nguyen Thai Ngoc DuyNext: Nguyen Thai Ngoc Duy
Message 33 of 48 in “Fix some errors reported by valgrind”
  1. 0/3 Fix some errors reported by valgrindCarlos Martín Nieto, Mar 14, 2011
  2. 1/3 make_absolute_path: Don't try to copy a string to itselfCarlos Martín Nieto, Mar 14, 2011
  3. Jeff KingMar 14, 2011
  4. Junio C HamanoMar 14, 2011
  5. Carlos Martín NietoMar 14, 2011
  6. Junio C HamanoMar 14, 2011
  7. Carlos Martín NietoMar 15, 2011
  8. Carlos Martín NietoMar 15, 2011
  9. Junio C HamanoMar 15, 2011
  10. Carlos Martín NietoMar 15, 2011
  11. Nguyen Thai Ngoc DuyMar 16, 2011
  12. Carlos Martín NietoMar 16, 2011
  13. Nguyen Thai Ngoc DuyMar 16, 2011
  14. Nguyen Thai Ngoc DuyMar 16, 2011
  15. Carlos Martín NietoMar 16, 2011
  16. 2/3 setup_path(): Free temporary bufferCarlos Martín Nieto, Mar 14, 2011
  17. Jeff KingMar 14, 2011
  18. Carlos Martín NietoMar 14, 2011
  19. system_path: use a static bufferCarlos Martín Nieto, Mar 16, 2011
  20. Erik Faye-LundMar 16, 2011
  21. Carlos Martín NietoMar 16, 2011
  22. system_path: use a static bufferCarlos Martín Nieto, Mar 16, 2011
  23. Junio C HamanoMar 16, 2011
  24. system_path: use a static bufferCarlos Martín Nieto, Mar 17, 2011
  25. system_path: use a static bufferCarlos Martín Nieto, Mar 17, 2011
  26. Junio C HamanoMar 18, 2011
  27. Carlos Martín NietoMar 21, 2011
  28. Jeff KingMar 21, 2011
  29. Carlos Martín NietoMar 21, 2011
  30. Jeff KingMar 21, 2011
  31. Carlos Martín NietoMar 21, 2011
  32. Nguyen Thai Ngoc DuyMar 18, 2011
  33. PATH_MAX (Re: [PATCH] system_path: use a static buffer)Jonathan Nieder, Mar 18, 2011
  34. Nguyen Thai Ngoc DuyMar 18, 2011
  35. Carlos Martín NietoMar 21, 2011
  36. Lasse MakholmMar 21, 2011
  37. Nguyen Thai Ngoc DuyMar 21, 2011
  38. 1/2 wrapper.c: add xgetcwd()Nguyễn Thái Ngọc Duy, Mar 18, 2011
  39. 2/2 setup_gently: use xgetcwd()Nguyễn Thái Ngọc Duy, Mar 18, 2011
  40. Junio C HamanoMar 14, 2011
  41. Carlos Martín NietoMar 14, 2011
  42. Jeff KingMar 15, 2011
  43. t/README: Add a note about running commands under valgrindCarlos Martín Nieto, Mar 15, 2011
  44. Junio C HamanoMar 15, 2011
  45. Carlos Martín NietoMar 15, 2011
  46. 3/3 clone: Free a few pathsCarlos Martín Nieto, Mar 14, 2011
  47. Jonathan NiederMar 14, 2011
  48. Junio C HamanoMar 18, 2011

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