Recursive mkdir system call on Unix

Question

After reading the mkdir 2  man page for the Unix system call with that name  it appears that the call doesn t create intermediate directories in a path  only the last directory in the path  Is there any way  or other function  to create all the directories in the path without resorting to manually parsing my directory string and individually creating each directory

User · Answer

Here s another take on mkpath    using recursion  which is both small and readable   It makes use of strdupa   to avoid altering the given dir string argument directly and to avoid using malloc    amp  free     Make sure to compile with -D GNU SOURCE to activate strdupa       meaning this code only works on GLIBC  EGLIBC  uClibc  and other GLIBC compatible C libraries   int mkpath char  dir  mode t mode        if   dir            errno   EINVAL          return 1             if  strlen dir     1  amp  amp  dir 0                  return 0       mkpath dirname strdupa dir    mode        return mkdir dir  mode       After input both here and from Valery Frolov  in the Inadyn project  the following revised version of mkpath   has now been pushed to libite  int mkpath char  dir  mode t mode        struct stat sb       if   dir            errno   EINVAL          return 1             if   stat dir   amp sb           return 0       mkpath dirname strdupa dir    mode        return mkdir dir  mode       It uses one more syscall  but otoh the code is more readable now

User · Answer

The two other answers given are for mkdir 1  and not mkdir 2  like you ask for  but you can look at the source code for that program and see how it implements the -p options which calls mkdir 2  repeatedly as needed

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hmm I thought that mkdir -p does that      mkdir -p this is a full path of stuff

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There is not a system call to do it for you  unfortunately   I m guessing that s because there isn t a way to have really well-defined semantics for what should happen in error cases   Should it leave the directories that have already been created   Delete them   What if the deletions fail  And so on     It is pretty easy to roll your own  however  and a quick google for  recursive mkdir  turned up a number of solutions   Here s one that was near the top   http   nion modprobe de blog archives 357-Recursive-directory-creation html  static void  mkdir const char  dir            char tmp 256           char  p   NULL          size t len           snprintf tmp  sizeof tmp    s  dir           len   strlen tmp           if tmp len - 1                          tmp len - 1    0          for p   tmp   1   p  p                    if  p                                    p   0                          mkdir tmp  S IRWXU                            p                                  mkdir tmp  S IRWXU

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My recursive way of doing this    include  lt libgen h gt     Only POSIX version of dirname       include  lt stdlib h gt   include  lt string h gt   include  lt sys stat h gt   include  lt sys types h gt   include  lt unistd h gt   static void recursive mkdir const char  path  mode t mode        char  spath   NULL      const char  next dir   NULL          dirname   modifies input         spath   strdup path       if  spath    NULL                   Report error  no memory left for string duplicate             goto done                Get next path component         next dir   dirname spath        if  access path  F OK     0                   The directory in question already exists             goto done             if  strcmp next dir          0    strcmp next dir          0                   We reached the end of recursion             goto done             recursive mkdir next dir  mode       if  mkdir path  mode     0                  Report error on creating directory           done      free spath       return      EDIT  fixed my old code snippet  bug-report by Namchester

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here is my solution void mkpath char  p        char  path   strdup p       char   save path   path      char  sep1      char  sep2 0      do           int idx    sep2-path  lt 0   0   sep2-path          sep1   strchr path   idx                     sep2   strchr sep1 1                if  sep2                path sep2-path  0                    if mkdir path  0777   amp  amp  errno    EEXIST              break          if  sep2                path sep2-path                       while  sep2        free save path             mkpath   quot   the new path quot

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Here s my shot at a more general solution    include  lt stdio h gt   include  lt string h gt   include  lt stdlib h gt   include  lt errno h gt   include  lt sys types h gt   include  lt sys stat h gt   typedef int   dirhandler t   const char   void         calls itfunc for each directory in path  except for   and     int iterate path  const char  path  dirhandler t itfunc  void  udata         int rv   0      char tmp  256        char  p   tmp      char  lp   tmp      size t len      size t sublen      int ignore entry       strncpy  tmp  path  255         tmp  255       0       len   strlen  tmp         if  0    len             1    len  amp  amp         tmp  0              return 0       if  tmp  len - 1                    tmp  len - 1     0       while   p   strchr  p            NULL                 ignore entry   0           p     0           lp   strrchr  tmp                  if  NULL    lp     lp   tmp            else   lp               sublen   strlen  lp             if  0    sublen        ignore things like                     ignore entry   1          else if  1    sublen  amp  amp      ignore things like                                  lp  0                 ignore entry   1          else if  2    sublen  amp  amp        also ignore things like                                   lp  0    amp  amp                          lp  1                 ignore entry   1           if    ignore entry                         if   rv   itfunc  tmp  udata       0                   return rv                      p                p            lp   p             if  strcmp  lp         amp  amp  strcmp  lp                   return itfunc  tmp  udata         return 0     mode t get file mode  const char  path         struct stat statbuf      memset   amp statbuf  0  sizeof  statbuf           if  NULL    path     return 0         if  0    stat  path   amp statbuf                   fprintf  stderr   failed to stat   s    s n                    path  strerror  errno              return 0             return statbuf st mode     static int mymkdir  const char  path  void  udata          void udata      int rv   mkdir  path  S IRWXU        int errnum   errno       if  0    rv                 if  EEXIST    errno  amp  amp              S ISDIR  get file mode  path           it s all good  the directory already exists                return 0           fprintf  stderr   mkdir   s   failed   s n                    path  strerror  errnum                   else                     fprintf  stderr   created directory   s n   path                  return rv     int mkdir with leading  const char  path         return iterate path  path  mymkdir  NULL       int main  int argc  const char   argv         size t i      int rv       if  argc  lt  2                 fprintf  stderr   usage   s  lt path gt    lt path gt      n                    argv  0              exit  1               for  i   1  i  lt  argc  i                   rv   mkdir with leading  argv  i              if  0    rv               return rv             return 0

User · Answer

Here is my solution  By calling the function below you ensure that all dirs leading to the file path specified exist  Note that file path argument is not directory name here but rather a path to a file that you are going to create after calling mkpath     Eg   mkpath   home me dir subdir file dat   0755  shall create  home me dir subdir if it does not exist  mkpath   home me dir subdir    0755  does the same   Works with relative paths as well   Returns -1 and sets errno in case of an error   int mkpath char  file path  mode t mode        assert file path  amp  amp   file path       for  char  p   strchr file path   1        p  p   strchr p   1                   p     0           if  mkdir file path  mode     -1                if  errno    EEXIST                     p                        return -1                                   p                  return 0      Note that file path is modified during the action but gets restored afterwards  Therefore file path is not strictly const

User · Answer

Apparently not  my two suggestions are   char dirpath 80      path to some directory   sprintf mkcmd   mkdir -p  s   dirpath   system mkcmd     Or if you don t want to use system   try looking at the coreutils mkdir source code and see how they implemented the -p option

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I m not allowed to comment on the first  and accepted  answer  not enough rep   so I ll post my comments as code in a new answer  The code below is based on the first answer  but fixes a number of problems    If called with a zero-length path  this does not read or write the character before the beginning of array opath    yes   why would you call it that way    but on the other hand  why would you not fix the vulnerability    the size of opath is now PATH MAX  which isn t perfect  but is better than a constant  if the path is as long as or longer than sizeof opath  then it is properly terminated when copied  which strncpy   doesn t do  you can specify the mode of the written directory  just as you can with the standard mkdir    although if you specify non-user-writeable or non-user-executable then the recursion won t work  main   returns the  required   int removed a few unnecessary  includes I like the function name better           Based on http   nion modprobe de blog archives 357-Recursive-directory-creation html  include  lt string h gt   include  lt sys stat h gt   include  lt unistd h gt   include  lt limits h gt   static void mkdirRecursive const char  path  mode t mode        char opath PATH MAX       char  p      size t len       strncpy opath  path  sizeof opath        opath sizeof opath  - 1      0       len   strlen opath       if  len    0          return      else if  opath len - 1                  opath len - 1      0       for p   opath   p  p            if   p                        p     0               if  access opath  F OK                   mkdir opath  mode                p                      if  access opath  F OK              if path is not terminated with              mkdir opath  mode       int main  void        mkdirRecursive   Users griscom one two three   S IRWXU       return 0

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My solution   int mkrdir const char  path  int index  int permission        char bf NAME MAX       if  path                 index        char  p   strchr path   index            int len      if p            len   MIN p-path  sizeof bf -1           strncpy bf  path  len           bf len  0        else           len   MIN strlen path  1  sizeof bf -1           strncpy bf  path  len           bf len  0             if access bf  0   0            mkdir bf  permission           if access bf  0   0                return -1                      if p            return mkrdir path  p-path 1  permission             return 0

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Take a look at the bash source code here  and specifically look in examples loadables mkdir c especially lines 136-210  If you don t want to do that  here s some of the source that deals with this  taken straight from the tar gz that I ve linked       Make all the directories leading up to PATH  then create PATH   Note that    this changes the process s umask  make sure that all paths leading to a    return reset it to ORIGINAL UMASK     static int make path  path  nmode  parent mode       char  path       int nmode  parent mode      int oumask    struct stat sb    char  p   npath     if  stat  path   amp sb     0            if  S ISDIR  sb st mode     0                    builtin error     s   file exists but is not a directory   path             return 1                 if  chmod  path  nmode                     builtin error    s   s   path  strerror  errno              return 1                 return 0         oumask   umask  0     npath   savestring  path         So we can write to it           Check whether or not we need to do anything with intermediate dirs           Skip leading slashes       p   npath    while   p             p       while  p   strchr  p                   p     0         if  stat  npath   amp sb     0                    if  mkdir  npath  parent mode                             builtin error   cannot create directory   s    s   npath  strerror  errno                  umask  original umask                 free  npath                 return 1                            else if  S ISDIR  sb st mode     0                    builtin error     s   file exists but is not a directory   npath             umask  original umask             free  npath             return 1                  p               restore slash          while   p                   p              Create the final directory component       if  stat  npath   amp sb   amp  amp  mkdir  npath  nmode             builtin error   cannot create directory   s    s   npath  strerror  errno          umask  original umask         free  npath         return 1         umask  original umask     free  npath     return 0      You can probably get away with a less general implementation

User · Answer

A very simple solution  just pass in input  mkdir dirname  void execute command mkdir char  input         char rec dir 500        int s       if strcmp input  mkdir      0          printf  mkdir  operand required        else                char  split   strtok input    t            while split                        if strcmp split  create dir      0                  strcpy rec dir split               split   strtok NULL     t                      char  split2   strtok rec dir               char dir 500           strcpy dir               while split2                        strcat dir split2               strcat dir                   printf   s  s n  split2 dir               s   mkdir dir 0700               split2   strtok NULL                         strcpy output  ok                  if s  lt  0              printf output  Error   Cannot Create Directory

User · Answer

Quite straight  This can be a good starting point  int makeDir char  fullpath  mode t permissions   int i 0  char  arrDirs 20   char aggrpaz 255   arrDirs i    strtok fullpath       strcpy aggrpaz        while arrDirs i   NULL        arrDirs   i    strtok NULL           strcat aggrpaz  arrDirs i-1        mkdir aggrpaz permissions       strcat aggrpaz          i 0  return 0      You parse this function a full path plus the permissions you want  i e S IRUSR  for a full list of modes go here https   techoverflow net 2013 04 05 how-to-use-mkdir-from-sysstat-h   The fullpath string will be split by the     character and individual dirs will be appended to the aggrpaz string one at a time  Each loop iteration calls the mkdir function  passing it the aggregate path so far plus the permissions  This example can be improved  I am not checking the mkdir function output and this function only works with absolute paths

[c] Recursive mkdir() system call on Unix

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