hashfile() yields a different output depending on the OS

[ThierryO]

Below is a reprex. This causes a bug in the git2rdata package when switching between OS (ropensci/git2rdata#49).

library(git2r)
filename <- tempfile("os-bug")
writeLines(
  c("x\ty", "1\t1", "2\t2", "3\t3", "4\t4", "5\t5", "6\t6", "7\t7", 
    "8\t8", "9\t9", "10\t10", "11\t11", "12\t12", "13\t13", "14\t14", 
    "15\t15", "16\t16", "17\t17", "18\t18", "19\t19", "20\t20", "21\t21", 
    "22\t22", "23\t23", "24\t24", "25\t25", "26\t26"),
  filename
)
hashfile(filename)

Output:

• Windows: 1de50dce6d5139f98a8e69d4d45d26ae7d32c64f
• Linux: 3e6fbe383532f4312bd0f5c9f30976f64d00e9cc

Session info on Windows

─ Session info ──────────────────────────────────────────────────────────────────────────────────
 setting  value                       
 version  R version 3.5.2 (2018-12-20)
 os       Windows >= 8 x64            
 system   x86_64, mingw32             
 ui       RStudio                     
 language (EN)                        
 collate  Dutch_Belgium.1252          
 ctype    Dutch_Belgium.1252          
 tz       Europe/Paris                
 date     2019-08-14                  

─ Packages ──────────────────────────────────────────────────────────────────────────────────────
 package     * version date       lib source        
 assertthat    0.2.1   2019-03-21 [1] CRAN (R 3.5.3)
 cli           1.1.0   2019-03-19 [1] CRAN (R 3.5.3)
 crayon        1.3.4   2017-09-16 [1] CRAN (R 3.5.3)
 drat          0.1.4   2017-12-16 [1] CRAN (R 3.5.3)
 fortunes      1.5-4   2016-12-29 [1] CRAN (R 3.5.2)
 git2r       * 0.25.2  2019-03-19 [1] CRAN (R 3.5.3)
 rstudioapi    0.10    2019-03-19 [1] CRAN (R 3.5.3)
 sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 3.5.3)
 withr         2.1.2   2018-03-15 [1] CRAN (R 3.5.3)
 yaml          2.2.0   2018-07-25 [1] CRAN (R 3.5.2)

[1] C:/R/library
[2] C:/Program Files/R/R-3.5.2/library

Session info on Linux

─ Session info ──────────────────────────────────────────────────────────────────────────────────
 setting  value                       
 version  R version 3.6.1 (2019-07-05)
 os       Ubuntu 18.04.3 LTS          
 system   x86_64, linux-gnu           
 ui       RStudio                     
 language nl:en                       
 collate  nl_NL.UTF-8                 
 ctype    nl_NL.UTF-8                 
 tz       Europe/Brussels             
 date     2019-08-14                  

─ Packages ──────────────────────────────────────────────────────────────────────────────────────
 package     * version date       lib source        
 assertthat    0.2.1   2019-03-21 [1] CRAN (R 3.6.0)
 cli           1.1.0   2019-03-19 [2] CRAN (R 3.5.3)
 crayon        1.3.4   2017-09-16 [2] CRAN (R 3.5.3)
 drat          0.1.5   2019-03-28 [1] CRAN (R 3.6.0)
 fortunes      1.5-4   2016-12-29 [1] CRAN (R 3.6.0)
 git2r         0.26.1  2019-06-29 [1] CRAN (R 3.6.0)
 packrat       0.5.0   2018-11-14 [1] CRAN (R 3.6.0)
 rstudioapi    0.10    2019-03-19 [2] CRAN (R 3.5.3)
 sessioninfo   1.1.1   2018-11-05 [2] CRAN (R 3.5.3)
 withr         2.1.2   2018-03-15 [2] CRAN (R 3.5.3)

[1] /home/thierry_onkelinx/R/x86_64-pc-linux-gnu-library/3.5
[2] /usr/local/lib/R/site-library
[3] /usr/lib/R/site-library
[4] /usr/lib/R/library

[stewid]

The reason you get a different hash between Linux and Windows is beacuse the file content is different in your example. When you use writeLines, it writes the line separator with a LF on Unix/Linux and CRLF on Windows, therefore, the hash is different.

If you rewrite the example to use writeChar instead to control the line endings, the hash should be identical between Linux and Windows.

library(git2r)
filename <- tempfile("test-file")
f <- file(filename, "wb")
writeChar(
    "x\ty\n1\t1\n2\t2\n3\t3\n4\t4\n5\t5\n6\t6\n7\t7\n8\t8\n9\t9\n10\t10\n11\t11\n12\t12\n13\t13\n14\t14\n15\t15\n16\t16\n17\t17\n18\t18\n19\t19\n20\t20\n21\t21\n22\t22\n23\t23\n24\t24\n25\t25\n26\t26\n",
    f,
    eos = NULL)
close(f)
hashfile(filename)